This document discusses various ways to optimize water-cooled cooling systems to reduce energy use. It describes how the efficiency of individual components like chillers and cooling towers has improved over time but greater savings are possible by optimizing overall system design and operation. Some strategies discussed include modulating cooling tower fan speed based on load to balance chiller and fan energy use, using closer cooling tower approach temperatures to lower chiller energy, controlling multi-cell tower fans simultaneously at lower speeds, and optimizing condenser water flow. Proper implementation of these strategies can significantly reduce cooling system energy use.
This presentation discusses data center cooling technologies. It provides a brief history of data centers and outlines ASHRAE thermal guidelines for operating envelopes and temperature change requirements. The presentation then reviews common cooling system types including computer room air conditioners, computer room air handlers, and water-side economizers. It also examines heat rejection options and trends toward higher supply air/water temperatures to improve efficiency.
The document provides an overview of HVAC systems, including key components and design considerations. It discusses the importance of HVAC for construction professionals due to costs, space requirements, and impact on building performance. The document then outlines the process of designing an HVAC system and various refrigeration, heating, cooling, and distribution options to consider. It provides pros and cons of different centralized and decentralized system types and highlights important coordination and specification details.
The presentation will include the following topics:
- Fundamentals of energy modeling
- Overview of the eQUEST energy modeling program
- Recommendations for integrating energy modeling into the design process
- Brief description of baseline energy modeling using ASHRAE Appendix G
- Recommended strategies for reducing energy use
- How to review energy modeling results
-Common problems and how to avoid them
Method to identify Building Energy Index BEISteve Lojuntin
Building Energy Index (BEI) or sometime known as Building Energy Intensity (BEI) or Energy Efficiency Index (EEI) are command work used in building energy management. BEI has been recognised as the primary Specific Energy Consumption (SEC). BEI representing the actual energy consumption.
Attached is the Standard BEI calculation used by Sustanable Energy Development Authority (SEDA) Malaysia, GreenTech Malaysia (formerly known as Malaysia Energy Centre), the government agencies, and professionals in Energy Management in Malaysia.
This document provides an overview of a course on heating, ventilating and air conditioning (HVAC) systems. The course objectives are to define air conditioning and refrigeration systems, discuss different types and applications, discuss terms associated with performance, and describe underlying scientific principles. Key topics covered include classification of HVAC systems, applications, refrigeration and air conditioning definitions, sensible and latent heat processes, heat transfer methods, and refrigeration capacity units.
Fired heaters are used for heating hydrocarbons fluids in the refineries and petrochemical plants. They are used for high temperature heat transfer. In most fired heaters, we are burning fuel gas as source of heat . There are many heaters in the world where liquid fuel is also burnt in the fired heaters to provide the energy, but their number is decreasing due to tighter pollution laws. Heaters that are processing hydrocarbons services are prone to coking and cracking depending upon the nature of the hydrocarbons being processed. Typically heaters may run length of anywhere from 3 months for coking service to 6 years for different services. Heater designers and operators are always faced with the challenge of providing uniform heat transfer to all the tubes. Engineers use equations that assume uniform heat transfer to heater tubes When designing fired heaters. However, in reality, most fired heaters do not experience uniform heat transfer, and as a result, hot spots develop on the tubes. These hot spots cause coking inside the tubes which requires the heater be shutdown periodically to remove the coke and clean the tubes. Any shutdown to clean the tubes in a fired heater causes a substantial production loss. The owners want to extend the run length of fired heaters. Furnace Improvements has developed a new patented firing technology that provides uniform heat transfer to heater tubes. This technology can be applied to most fired heaters. Our patented technology reorients the burners at a slight angle away from the tubes. We are able to direct the hottest part of the flames and flue gases away from the tubes without affecting the heat transfer in any way. FIS has installed this in 5 heaters ranging from 14 MMBtu/hr. to 280 MMBtu/hr. The clients are experiencing significant reduction in tube metal temperatures. This is translating into lower coking rates and higher tube life. We have been able to increase the capacity of the heaters in most of the cases. In one of the case study that has been presented in this heater, the heater duty was increased from 14 MMBtu/hr. to 21 MMBtu/hr. Inclined firing improves the heat transfer to the tubes and makes in uniform.
The document discusses India's Energy Conservation Building Code (ECBC). It aims to set minimum energy efficiency standards for building design and construction. The ECBC encourages energy efficient practices that do not compromise occupant comfort or economic considerations. It provides the central and state governments powers to enforce compliance. The ECBC is estimated to reduce building energy use by 25-40% through requirements for the building envelope, lighting, HVAC, and other systems. Widespread adoption could yield annual national energy savings of over 1.7 billion kWh. Implementation faces barriers around first costs, product availability, and testing/certification.
This presentation discusses data center cooling technologies. It provides a brief history of data centers and outlines ASHRAE thermal guidelines for operating envelopes and temperature change requirements. The presentation then reviews common cooling system types including computer room air conditioners, computer room air handlers, and water-side economizers. It also examines heat rejection options and trends toward higher supply air/water temperatures to improve efficiency.
The document provides an overview of HVAC systems, including key components and design considerations. It discusses the importance of HVAC for construction professionals due to costs, space requirements, and impact on building performance. The document then outlines the process of designing an HVAC system and various refrigeration, heating, cooling, and distribution options to consider. It provides pros and cons of different centralized and decentralized system types and highlights important coordination and specification details.
The presentation will include the following topics:
- Fundamentals of energy modeling
- Overview of the eQUEST energy modeling program
- Recommendations for integrating energy modeling into the design process
- Brief description of baseline energy modeling using ASHRAE Appendix G
- Recommended strategies for reducing energy use
- How to review energy modeling results
-Common problems and how to avoid them
Method to identify Building Energy Index BEISteve Lojuntin
Building Energy Index (BEI) or sometime known as Building Energy Intensity (BEI) or Energy Efficiency Index (EEI) are command work used in building energy management. BEI has been recognised as the primary Specific Energy Consumption (SEC). BEI representing the actual energy consumption.
Attached is the Standard BEI calculation used by Sustanable Energy Development Authority (SEDA) Malaysia, GreenTech Malaysia (formerly known as Malaysia Energy Centre), the government agencies, and professionals in Energy Management in Malaysia.
This document provides an overview of a course on heating, ventilating and air conditioning (HVAC) systems. The course objectives are to define air conditioning and refrigeration systems, discuss different types and applications, discuss terms associated with performance, and describe underlying scientific principles. Key topics covered include classification of HVAC systems, applications, refrigeration and air conditioning definitions, sensible and latent heat processes, heat transfer methods, and refrigeration capacity units.
Fired heaters are used for heating hydrocarbons fluids in the refineries and petrochemical plants. They are used for high temperature heat transfer. In most fired heaters, we are burning fuel gas as source of heat . There are many heaters in the world where liquid fuel is also burnt in the fired heaters to provide the energy, but their number is decreasing due to tighter pollution laws. Heaters that are processing hydrocarbons services are prone to coking and cracking depending upon the nature of the hydrocarbons being processed. Typically heaters may run length of anywhere from 3 months for coking service to 6 years for different services. Heater designers and operators are always faced with the challenge of providing uniform heat transfer to all the tubes. Engineers use equations that assume uniform heat transfer to heater tubes When designing fired heaters. However, in reality, most fired heaters do not experience uniform heat transfer, and as a result, hot spots develop on the tubes. These hot spots cause coking inside the tubes which requires the heater be shutdown periodically to remove the coke and clean the tubes. Any shutdown to clean the tubes in a fired heater causes a substantial production loss. The owners want to extend the run length of fired heaters. Furnace Improvements has developed a new patented firing technology that provides uniform heat transfer to heater tubes. This technology can be applied to most fired heaters. Our patented technology reorients the burners at a slight angle away from the tubes. We are able to direct the hottest part of the flames and flue gases away from the tubes without affecting the heat transfer in any way. FIS has installed this in 5 heaters ranging from 14 MMBtu/hr. to 280 MMBtu/hr. The clients are experiencing significant reduction in tube metal temperatures. This is translating into lower coking rates and higher tube life. We have been able to increase the capacity of the heaters in most of the cases. In one of the case study that has been presented in this heater, the heater duty was increased from 14 MMBtu/hr. to 21 MMBtu/hr. Inclined firing improves the heat transfer to the tubes and makes in uniform.
The document discusses India's Energy Conservation Building Code (ECBC). It aims to set minimum energy efficiency standards for building design and construction. The ECBC encourages energy efficient practices that do not compromise occupant comfort or economic considerations. It provides the central and state governments powers to enforce compliance. The ECBC is estimated to reduce building energy use by 25-40% through requirements for the building envelope, lighting, HVAC, and other systems. Widespread adoption could yield annual national energy savings of over 1.7 billion kWh. Implementation faces barriers around first costs, product availability, and testing/certification.
District Cooling Service - Presentation to Qatar RailJaygopal Kottilil
This document discusses district cooling services in the GCC region. It provides background on district cooling, including its history in North America and Europe. It then discusses the growth of district cooling in the GCC, forecasting a need for 2 million refrigerant tons of cooling capacity for new construction projects over the next 8-10 years. The document analyzes the benefits of district cooling systems over individual building cooling systems, such as improved reliability and reduced energy usage. It also provides several case studies comparing the capital and operating costs of district cooling versus other cooling solutions. The analysis shows that district cooling can be economically viable for large developments if capital costs are optimized and utilities such as treated seawater are consistently available.
This document provides an application and installation guide for Cummins generator sets. It includes sections on standards, regulations, recommended room sizes and layouts, fuel systems, exhaust systems, cooling systems, starting systems, control systems, soundproofing, dimensions, weights, and technical data. The guide details considerations for planning, installing, and commissioning generator set installations according to relevant regulations and safety standards.
There are two main types of cooling towers: natural draft and mechanical draft. Natural draft towers use large chimneys to introduce air and are used for large water flows over 45,000 m3/hr in power stations. Mechanical draft towers use fans and have designs that are counter flow induced draft, counter flow forced draft, or cross flow induced draft. The basic components of a cooling tower include a frame and casing, fill to maximize air and water contact, a cold water basin, drift eliminators, an air inlet, louvers, nozzles, and fans.
This document provides an overview of ASHRAE 90.1-2004 Appendix G Performance Rating Method, which provides modeling rules for rating building designs that aim to exceed minimum energy code compliance. It describes key aspects of the performance rating method including how it allows for more flexible modeling of energy efficiency measures compared to a basic code compliance model. It also summarizes federal building energy efficiency requirements and LEED rating systems that reference Appendix G for demonstrating energy savings above minimum standards.
The document discusses smoke extraction in buildings, including key factors in smoke extraction design such as design fire size, smoke layer depth, smoke reservoirs, minimum number of extract points, inlet air, ductwork, and performance criteria for fire resisting ductwork. Effective smoke extraction requires considering smoke pathways, production, and movement, and extraction methods vary depending on building type, such as for multi-story offices, warehouses, underground parking, atriums, and shopping malls. Following approved agency guidance can significantly reduce fire and smoke threats.
Original presentation by Glenn Friedman and presented to the Illinois Chapter of ASHRAE at the May 10 monthly meeting by Michael Kuk of Sieben Energy Associates.
When developing data center energy-use estimations, engineers must account for all sources of energy use in the facility. Most energy consumption is obvious: computers, cooling plant and related equipment, lighting, and other miscellaneous electrical loads. Designing efficient and effective data centers is a top priority for consulting engineers. Cooling is a large portion of data center energy use, second only to the IT load. Although there are several options to help maximize HVAC efficiency and minimize energy consumption, data centers come in many shapes, sizes, and configurations. By developing a deep understanding of their client’s data center HVAC requirements, consulting engineers can help maintain the necessary availability level of mission critical applications while reducing energy consumption.
A cooling tower is a heat rejection device which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature.
A cooling tower is a heat rejection device which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature.
Common applications include cooling the circulating water used in oil refineries, petrochemical and other chemical plants, thermal power stations and HVAC systems for cooling buildings. The classification is based on the type of air induction into the tower: the main types of cooling towers are natural draft and induced draft cooling towers.
Cooling towers vary in size from small roof-top units to very large hyperboloid structures (as in the adjacent image) that can be up to 200 metres (660 ft) tall and 100 metres (330 ft) in diameter, or rectangular structures that can be over 40 metres (130 ft) tall and 80 metres (260 ft) long. The hyperboloid cooling towers are often associated with nuclear power plants,[1] although they are also used to some extent in some large chemical and other industrial plants. Although these large towers are very prominent, the vast majority of cooling towers are much smaller, including many units installed on or near buildings to discharge heat from air conditioning.
This document discusses HVAC systems and their energy consumption. It describes how HVAC systems maintain temperature, humidity, and ventilation levels in buildings. HVAC systems circulate air through air handling units, which heat, cool, filter and distribute air to rooms using boilers, chillers, pumps, and other mechanical equipment located in mechanical rooms. The document explains the functions of key HVAC components like AHUs, VAV boxes, economizers and how they work to condition air and ensure thermal comfort. It also notes some differences that can occur between theoretical HVAC diagrams and real-world systems.
Radiant cooling for residential and commercial applications (Messana Radiant ...Alessandro Arnulfo
Hydronic radiant cooling systems have been used worldwide for decades. Now are gaining popularity also in North America and become an effective alternative to traditional all-air systems. New building codes and regulations demand for more energy efficient HVAC systems and radiant cooling is a proven an effective technology for cooling residential and commercial buildings. It is the preferred choice for designers to meet standards of Passive House, NetZero energy buildings, green and sustainable architecture. This presentation will address common questions and concerns and also analyze some of the benefits in terms of thermal comfort, wellbeing and productivity of occupants as well as substantial reduction of ductwork cross-sectional dimensions, operational and maintenance costs. Several case studies of radiant cooling projects will be presented.
This document provides an overview of HVAC (heating, ventilation, and air conditioning) systems. It defines HVAC as the control of air temperature, moisture content, and proper air movement to maintain acceptable air quality. It then describes common HVAC applications in buildings and industries. The document outlines the basic components and operating cycle of air conditioning systems. It also discusses factors to consider when selecting and designing HVAC systems, such as cooling load calculations, equipment types, ducting, and air distribution. Finally, it covers recent trends toward more energy efficient HVAC equipment and controls.
Energy efficiency in building-the way toward low carbon development-nov 2021Tantish QS, UTM
A document discusses energy efficient buildings and low carbon development in Malaysia. It provides three key points:
1) Building energy usage is a major contributor to greenhouse gas emissions. Transitioning to more efficient green buildings is an important part of Malaysia's commitment to low carbon development.
2) The government has implemented policies and guidelines since 2010 to promote green technology and low carbon buildings. Examples of efficient buildings constructed by the government aim to catalyze green building practices.
3) An energy management approach is important for designing and operating efficient buildings. Case studies demonstrate how energy efficiency strategies, monitoring, and user awareness can significantly reduce buildings' energy usage and carbon footprint.
This document discusses the equal-friction method of designing an air conditioning system duct layout to distribute 36,000 cfm of air through 18 outlets at 0.2 in wg pressure. [1] It outlines the steps to size the main duct at 46x46 inches and branch ducts to maintain equal friction. [2] Calculations determine the total duct friction loss is 0.3315 in wg. [3] The required fan static discharge pressure is calculated to be 0.3215 in wg.
Cooling Optimization 101: A Beginner's Guide to Data Center CoolingUpsite Technologies
As new personnel enter the industry, they are often bombarded with a slew of buzz words and marketing messages that would lead them to believe that data centers almost run themselves. And while monitoring and DCIM solutions are improving the management of power and cooling, an understanding of the fundamental science is crucial to both see through the hype and get the most out of management systems. More so, as the veterans in our industry start to retire, much of the basic knowledge around power and cooling is often overlooked when training their successors. This session will provide that basic knowledge and give a fundamental understanding of the power and cooling infrastructure in a data center, with an emphasis on cooling optimization. In this session, you’ll learn how to recover stranded cooling capacity, reduce operating costs, improve IT equipment reliability, and prolong the life and capacity of the data center.
Delivering an Energy Model for BREEAM and LEED – Exposing What Really Matters...IES VE
This presentation looks at the technical perspectives of delivering an energy model for both the purposes of different regulatory frameworks; LEED and BREEAM. The technical focus will be upon the metrics used and design strategies that affect the performance, certification and rating of buildings.
Decarbonisation Futures: Innovation Pathways to Net Zero EmissionsIEA-ETSAP
The document summarizes a presentation by ClimateWorks Australia on innovation scenarios for achieving net zero emissions. It discusses ClimateWorks' mission to advise on accelerating the transition to net zero emissions through research and action. Three key drivers for decarbonization are identified: technology improvements, policy shifts, and societal changes. The presentation outlines ClimateWorks' scenario analysis approach, which models pathways to meet temperature goals based on varying levels of influence from the three drivers. Disruptive technologies across sectors that could significantly impact decarbonization pathways are also assessed.
The segmentation of data centers into alternating hot and cold aisles is an established best practice. A number of manufacturers are taking this premise of airflow separation a step further by marketing "containment" solutions. By containing the hot or cold aisle, the air paths have little chance to mix, presenting data center operators with both reliability and efficiency gains.
To view the recording of the webinar presentation, please visit http://www.42u.com/webinars/Aisle-Containment-Webinar/playback.htm
This document provides an overview of cooling towers including:
- A brief history noting the development of condensers for steam engines in the 19th century leading to early cooling towers on rooftops or as free-standing structures.
- An explanation of the two main types of cooling towers - natural draft towers which rely on natural airflow and mechanical draft towers which use induced fans. Counter-flow and cross-flow arrangements within each type are also described.
- Key terminology used in cooling towers is defined, such as drift, blow-out, plume, draw-off, make-up, range, fill types, and common structural materials.
The document discusses forced draft cooling towers and their components. It describes the key parts including fans, drift eliminators, fills, nozzles, and basins. It also covers topics like packing materials, water and salt balances, windage losses, heat balances, biocides, chlorine dioxide production, and links to additional resources.
District Cooling Service - Presentation to Qatar RailJaygopal Kottilil
This document discusses district cooling services in the GCC region. It provides background on district cooling, including its history in North America and Europe. It then discusses the growth of district cooling in the GCC, forecasting a need for 2 million refrigerant tons of cooling capacity for new construction projects over the next 8-10 years. The document analyzes the benefits of district cooling systems over individual building cooling systems, such as improved reliability and reduced energy usage. It also provides several case studies comparing the capital and operating costs of district cooling versus other cooling solutions. The analysis shows that district cooling can be economically viable for large developments if capital costs are optimized and utilities such as treated seawater are consistently available.
This document provides an application and installation guide for Cummins generator sets. It includes sections on standards, regulations, recommended room sizes and layouts, fuel systems, exhaust systems, cooling systems, starting systems, control systems, soundproofing, dimensions, weights, and technical data. The guide details considerations for planning, installing, and commissioning generator set installations according to relevant regulations and safety standards.
There are two main types of cooling towers: natural draft and mechanical draft. Natural draft towers use large chimneys to introduce air and are used for large water flows over 45,000 m3/hr in power stations. Mechanical draft towers use fans and have designs that are counter flow induced draft, counter flow forced draft, or cross flow induced draft. The basic components of a cooling tower include a frame and casing, fill to maximize air and water contact, a cold water basin, drift eliminators, an air inlet, louvers, nozzles, and fans.
This document provides an overview of ASHRAE 90.1-2004 Appendix G Performance Rating Method, which provides modeling rules for rating building designs that aim to exceed minimum energy code compliance. It describes key aspects of the performance rating method including how it allows for more flexible modeling of energy efficiency measures compared to a basic code compliance model. It also summarizes federal building energy efficiency requirements and LEED rating systems that reference Appendix G for demonstrating energy savings above minimum standards.
The document discusses smoke extraction in buildings, including key factors in smoke extraction design such as design fire size, smoke layer depth, smoke reservoirs, minimum number of extract points, inlet air, ductwork, and performance criteria for fire resisting ductwork. Effective smoke extraction requires considering smoke pathways, production, and movement, and extraction methods vary depending on building type, such as for multi-story offices, warehouses, underground parking, atriums, and shopping malls. Following approved agency guidance can significantly reduce fire and smoke threats.
Original presentation by Glenn Friedman and presented to the Illinois Chapter of ASHRAE at the May 10 monthly meeting by Michael Kuk of Sieben Energy Associates.
When developing data center energy-use estimations, engineers must account for all sources of energy use in the facility. Most energy consumption is obvious: computers, cooling plant and related equipment, lighting, and other miscellaneous electrical loads. Designing efficient and effective data centers is a top priority for consulting engineers. Cooling is a large portion of data center energy use, second only to the IT load. Although there are several options to help maximize HVAC efficiency and minimize energy consumption, data centers come in many shapes, sizes, and configurations. By developing a deep understanding of their client’s data center HVAC requirements, consulting engineers can help maintain the necessary availability level of mission critical applications while reducing energy consumption.
A cooling tower is a heat rejection device which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature.
A cooling tower is a heat rejection device which extracts waste heat to the atmosphere through the cooling of a water stream to a lower temperature. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or, in the case of closed circuit dry cooling towers, rely solely on air to cool the working fluid to near the dry-bulb air temperature.
Common applications include cooling the circulating water used in oil refineries, petrochemical and other chemical plants, thermal power stations and HVAC systems for cooling buildings. The classification is based on the type of air induction into the tower: the main types of cooling towers are natural draft and induced draft cooling towers.
Cooling towers vary in size from small roof-top units to very large hyperboloid structures (as in the adjacent image) that can be up to 200 metres (660 ft) tall and 100 metres (330 ft) in diameter, or rectangular structures that can be over 40 metres (130 ft) tall and 80 metres (260 ft) long. The hyperboloid cooling towers are often associated with nuclear power plants,[1] although they are also used to some extent in some large chemical and other industrial plants. Although these large towers are very prominent, the vast majority of cooling towers are much smaller, including many units installed on or near buildings to discharge heat from air conditioning.
This document discusses HVAC systems and their energy consumption. It describes how HVAC systems maintain temperature, humidity, and ventilation levels in buildings. HVAC systems circulate air through air handling units, which heat, cool, filter and distribute air to rooms using boilers, chillers, pumps, and other mechanical equipment located in mechanical rooms. The document explains the functions of key HVAC components like AHUs, VAV boxes, economizers and how they work to condition air and ensure thermal comfort. It also notes some differences that can occur between theoretical HVAC diagrams and real-world systems.
Radiant cooling for residential and commercial applications (Messana Radiant ...Alessandro Arnulfo
Hydronic radiant cooling systems have been used worldwide for decades. Now are gaining popularity also in North America and become an effective alternative to traditional all-air systems. New building codes and regulations demand for more energy efficient HVAC systems and radiant cooling is a proven an effective technology for cooling residential and commercial buildings. It is the preferred choice for designers to meet standards of Passive House, NetZero energy buildings, green and sustainable architecture. This presentation will address common questions and concerns and also analyze some of the benefits in terms of thermal comfort, wellbeing and productivity of occupants as well as substantial reduction of ductwork cross-sectional dimensions, operational and maintenance costs. Several case studies of radiant cooling projects will be presented.
This document provides an overview of HVAC (heating, ventilation, and air conditioning) systems. It defines HVAC as the control of air temperature, moisture content, and proper air movement to maintain acceptable air quality. It then describes common HVAC applications in buildings and industries. The document outlines the basic components and operating cycle of air conditioning systems. It also discusses factors to consider when selecting and designing HVAC systems, such as cooling load calculations, equipment types, ducting, and air distribution. Finally, it covers recent trends toward more energy efficient HVAC equipment and controls.
Energy efficiency in building-the way toward low carbon development-nov 2021Tantish QS, UTM
A document discusses energy efficient buildings and low carbon development in Malaysia. It provides three key points:
1) Building energy usage is a major contributor to greenhouse gas emissions. Transitioning to more efficient green buildings is an important part of Malaysia's commitment to low carbon development.
2) The government has implemented policies and guidelines since 2010 to promote green technology and low carbon buildings. Examples of efficient buildings constructed by the government aim to catalyze green building practices.
3) An energy management approach is important for designing and operating efficient buildings. Case studies demonstrate how energy efficiency strategies, monitoring, and user awareness can significantly reduce buildings' energy usage and carbon footprint.
This document discusses the equal-friction method of designing an air conditioning system duct layout to distribute 36,000 cfm of air through 18 outlets at 0.2 in wg pressure. [1] It outlines the steps to size the main duct at 46x46 inches and branch ducts to maintain equal friction. [2] Calculations determine the total duct friction loss is 0.3315 in wg. [3] The required fan static discharge pressure is calculated to be 0.3215 in wg.
Cooling Optimization 101: A Beginner's Guide to Data Center CoolingUpsite Technologies
As new personnel enter the industry, they are often bombarded with a slew of buzz words and marketing messages that would lead them to believe that data centers almost run themselves. And while monitoring and DCIM solutions are improving the management of power and cooling, an understanding of the fundamental science is crucial to both see through the hype and get the most out of management systems. More so, as the veterans in our industry start to retire, much of the basic knowledge around power and cooling is often overlooked when training their successors. This session will provide that basic knowledge and give a fundamental understanding of the power and cooling infrastructure in a data center, with an emphasis on cooling optimization. In this session, you’ll learn how to recover stranded cooling capacity, reduce operating costs, improve IT equipment reliability, and prolong the life and capacity of the data center.
Delivering an Energy Model for BREEAM and LEED – Exposing What Really Matters...IES VE
This presentation looks at the technical perspectives of delivering an energy model for both the purposes of different regulatory frameworks; LEED and BREEAM. The technical focus will be upon the metrics used and design strategies that affect the performance, certification and rating of buildings.
Decarbonisation Futures: Innovation Pathways to Net Zero EmissionsIEA-ETSAP
The document summarizes a presentation by ClimateWorks Australia on innovation scenarios for achieving net zero emissions. It discusses ClimateWorks' mission to advise on accelerating the transition to net zero emissions through research and action. Three key drivers for decarbonization are identified: technology improvements, policy shifts, and societal changes. The presentation outlines ClimateWorks' scenario analysis approach, which models pathways to meet temperature goals based on varying levels of influence from the three drivers. Disruptive technologies across sectors that could significantly impact decarbonization pathways are also assessed.
The segmentation of data centers into alternating hot and cold aisles is an established best practice. A number of manufacturers are taking this premise of airflow separation a step further by marketing "containment" solutions. By containing the hot or cold aisle, the air paths have little chance to mix, presenting data center operators with both reliability and efficiency gains.
To view the recording of the webinar presentation, please visit http://www.42u.com/webinars/Aisle-Containment-Webinar/playback.htm
This document provides an overview of cooling towers including:
- A brief history noting the development of condensers for steam engines in the 19th century leading to early cooling towers on rooftops or as free-standing structures.
- An explanation of the two main types of cooling towers - natural draft towers which rely on natural airflow and mechanical draft towers which use induced fans. Counter-flow and cross-flow arrangements within each type are also described.
- Key terminology used in cooling towers is defined, such as drift, blow-out, plume, draw-off, make-up, range, fill types, and common structural materials.
The document discusses forced draft cooling towers and their components. It describes the key parts including fans, drift eliminators, fills, nozzles, and basins. It also covers topics like packing materials, water and salt balances, windage losses, heat balances, biocides, chlorine dioxide production, and links to additional resources.
Pump and cooling tower energy performancemaulik610
This document provides an overview of pumps and cooling towers used in industrial applications. It discusses the main components, types, and operating characteristics of pumps, including centrifugal pumps which account for 75% of installed pumps. The document also examines how to assess pump performance by calculating parameters like pump shaft power and hydraulic power. For cooling towers, it outlines the components and types, and explains how to evaluate cooling tower performance using metrics such as range, approach, effectiveness, cooling capacity, and evaporation loss. The document concludes by identifying opportunities to improve the energy efficiency of pumps and cooling towers through equipment selection and optimization.
Water Conservation - Cooling Tower Management Overview brentmwhite
Cooling towers use significant amounts of water for processes like air conditioning and refrigeration. They are one of the largest water users in places like hospitals, hotels, and office buildings. Cooling towers work by evaporating a small portion of water to lower the temperature of the remaining water in an efficient closed-loop system. There are two main types of cooling tower designs, and water is lost primarily through evaporation, bleed-off of concentrated water, and minor drift. Increasing the concentration ratio by reducing bleed-off through improved monitoring, treatment, and alternative water sources can significantly conserve water use.
The document discusses cooling towers, including:
1. Types of cooling towers like natural draft, mechanical draft, forced draft, induced draft, cross flow and counter flow towers.
2. Parameters for assessing cooling tower performance including range, approach, effectiveness and cooling capacity.
3. Energy efficiency opportunities like selecting an appropriately sized tower, using efficient fill media to reduce pumping needs, and optimizing fans and motors.
There are two main types of cooling towers: natural draft and mechanical draft. Mechanical draft towers use large fans to force or suck air through circulated water and come in designs like counter flow induced draft, counter flow forced draft, and cross flow induced draft. A cooling tower consists of a frame and casing, fill material, cold water basin, drift eliminators, air inlet, nozzles, and fans. Factors like fill material, approach, flow rate, range, heat load, and wet bulb temperature affect cooling tower performance. Efficient operation involves water treatment, minimizing drift loss, optimizing fans and pumps, and evaluating opportunities for energy savings.
The document provides details of a cooling tower renovation project at a fertilizer plant. Key points:
- The existing cooling tower packing, drift eliminators, and nozzles needed replacement as their working life had expired after 7-10 years.
- Modifications included installing new packing, drift eliminators, dynamic Ecojet nozzles, and a vibration monitoring system.
- The project was completed on time and under budget using mostly local labor. It is expected to improve cooling tower performance and reliability.
- Lessons learned include using local labor for most tasks and marking scaffolding pipes to streamline future work. The renovation reduced circulating water temperature ranges and approach.
This newsletter discusses optimizing condenser water system design and control to reduce installation and operating costs. It recommends designing systems with lower condenser water flow rates (1.9 gpm/ton) and larger temperature differences (15°F ΔT) based on industry guidance. This allows reducing pipe sizes, pump capacity, and cooling tower fan power. Near-optimal control of cooling tower fan speed alone can save 2-14% of annual operating costs depending on climate. Controlling both fan and pump speeds more precisely may further reduce costs but requires more complex control strategies to account for interactions between components.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document discusses applying a vacuum ice thermal storage (VIM TES) system to a peaking gas turbine power plant to improve performance and reduce costs. The VIM TES system would produce ice slurry to cool the gas turbine's compressor inlet, allowing it to operate at lower temperatures than the existing chiller system. Modeling shows the VIM TES could decrease chiller parasitic power consumption by 25% and increase the turbine's net power output by 12% compared to the current system. The feasibility analysis is based on operational data from the plant's 47MW gas turbine over one year.
Turbine Inlet Air Cooling (TIAC) - Case Studies - Economics - Performance - C...Salman Haider
Efficiency Enhancement of a Gas Turbine in Hot climate conditions. Design strategies and technology varieties. Detailed Case Studies of TIAC equipped power plants, economic and performance analysis. Study of Climate effect on GT Performance in three different locations.
This document discusses using a water mist pre-cooling system to improve the efficiency of air-cooled chillers. It first provides background on how air-cooled chillers work and their relatively low efficiency compared to water-cooled chillers. It then discusses how using evaporative cooling techniques like water mist can lower the temperature of air entering the condenser, lowering the condensing temperature and improving chiller efficiency. The document goes on to describe modeling done to analyze the performance of a chiller system equipped with a water mist pre-cooler under different control strategies. The modeling results suggest water mist pre-cooling can increase chiller COP when combined with variable condenser temperature control.
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How do i optimize industrial refrigeration systemAlaquainc
In processing equipment services, processors should focus on five stages to get the most out of a contemporary industrial refrigeration system:
• Lowering the costs of installation and maintenance
• Improving productivity
• Assuring the food safety
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• Switching to more environmentally friendly refrigerants
Combining techniques can bring a number of advantages. This post will look at five techniques to improve the efficiency of industrial refrigeration systems.
lecture 3 - COMPRESSED AIR ENERGY STORAGE.pdfDinaSaad22
Compressed air energy storage systems store energy by compressing air and storing it in underground reservoirs like depleted gas fields. When energy demand is high, the compressed air is released to drive turbines and generate electricity. There are two main types - diabatic systems that release heat during compression and require external heating for expansion, and adiabatic systems that store heat from compression and use it for expansion. Compressed gas energy storage uses other gases like CO2 instead of air and can couple with CO2 capture benefits.
This document discusses several methods for optimizing energy consumption in air conditioning plant systems, including improving chiller efficiency, fan power, humidity controls, cooling tower efficiency, chilled/condenser water pumps, chiller plant system control, under-floor systems, and energy recovery systems. It provides case studies on topics like chiller plant design concepts, efficient component selection, installation, commissioning, and operation to reduce energy usage by 30-50%.
This document discusses water-side heat recovery from chillers. It provides context on the history of heat recovery use in the 1970s during an energy crisis and its renewed interest today due to rising energy costs and environmental regulations. It then covers various types of heat recovery systems using single or dual condenser chillers, appropriate water temperatures for heat recovery, and the impact of heat recovery on chiller capacity and efficiency depending on compressor type. The optimal approach is to recover heat at the lowest possible temperature to satisfy loads while minimizing additional chiller energy use.
The document discusses cooling challenges for data centers and presents various cooling solutions. Specifically, it notes that cooling now accounts for 60-70% of data center energy costs. It then outlines challenges like increasing power densities and need for efficiency, availability, manageability, and serviceability. Various cooling architectures are presented, including room-based cooling, row-based cooling, and close-coupled cooling. Free cooling options using ambient air are also discussed.
DC inverter technology provides energy savings and other benefits for HVAC-R applications. It allows compressors and other components to precisely modulate capacity based on load. This improves efficiency, temperature control, reliability, and noise levels. It also enables use of natural refrigerants and adaptation to varying loads. DC technology generates data that can be analyzed for process optimization through key performance indicators, benchmarking, and reports. This helps reduce operational costs and food waste while improving food preservation and profitability.
1. The study compared the power consumption of air cooling versus water cooling for an extrusion process using four different resins.
2. Water cooling used slightly more energy than air cooling for all resins, with the greatest difference seen in PET where water cooling used 80% more energy.
3. Air cooling is recommended for dedicated processes as it provides sufficient cooling with less energy use than water cooling, however the screw design must match the resin to avoid excessive heating or cooling needs.
01 thermal energy storage using ice slurryWahid Mohamed
This document discusses thermal energy storage using ice slurry. It begins with an introduction to thermal energy storage, including sensible energy storage using water and latent cool storage technologies. It defines ice slurry as a suspension of ice crystals in liquid. The document outlines the components of an ice slurry generator system, including schematics of different configurations. It notes benefits like higher energy transport density and consistently cool temperatures near the phase change point. Applications include district cooling systems, and case studies demonstrate cost savings from peak shaving and improved chiller efficiency.
Development of a Bench-Top Air-to-Water Heat Pump Experimental ApparatusCSCJournals
The document describes the development of a bench-top air-to-water heat pump experimental apparatus for educational purposes. Key features include:
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This document discusses equipment used in liquefied natural gas (LNG) processing plants, including compressors, gas turbines, and cryogenic equipment. It describes various types of compressors like reciprocating and screw compressors, and gas turbines like aeroderivative and industrial turbines. It explains their operating principles, advantages, disadvantages and applications in LNG plants. Gas turbines can drive centrifugal compressors and are used in simple or combined cycle configurations for power generation. Cryogenic pumps and heat exchangers are also discussed.
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Improving boiler efficiency by using air preheaterNetha Jashuva
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A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
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Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
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This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
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1. A S H R A E J O U R N A L ashrae.org FEBRUARY 201434
Since then, water-cooled systems have steadily
improved their performance. For instance, the effi-
ciency of a 500 ton (1757 kW) water-cooled centrifugal
chiller has improved by over 50% since 19751 as indi-
cated by the requirements of ASHRAE/IES Standard 90.1
(hereafter referred to as Standard 90.1). Cooling towers
have also evolved from centrifugal fan units to much
more energy-efficient axial fan designs with improved
heat transfer surfaces, known as fill. In addition, inde-
pendent certification of thermal performance for open
circuit cooling towers per the Cooling Technology
Institute’s Standard 201* has become widely accepted in
the marketplace and became required by Standard 90.1
in the 2007 edition.
While the efficiency improvements of individual sys-
tem components have certainly lowered overall energy
use, even greater improvements are possible by optimiz-
ing the way cooling systems are designed and operated.
For instance, the full load energy use in a 500 ton (1757
kW) water-cooled chiller system, based on Standard
90.1-2013 minimum efficiencies, is roughly broken
down as follows: chiller – 77%, cooling tower – 8%, con-
denser pump – 7%, and chilled water pump – 8%. With
the chiller accounting for the majority of the energy use,
many contend that it makes sense to operate the cooling
tower fan and condenser pump such that compressor
energy use is reduced—since it is by far the largest motor
in the system.
For instance, to lower chiller energy, the cooling tower
is often operated at full fan speed and flow until ambi-
ent conditions allow the minimum condenser water
temperature limit to be reached. Below this level, the
fan speed of the cooling tower is modulated, typically
by a variable speed drive (VSD), to maintain the set-
point. This is essentially the operating sequence for the
water-cooled baseline buildings found in Appendix
G of Standard 90.1-2013, which uses 70°F (21.1°C) as
the lower condenser water setpoint (though this value
Water-cooled systems offer lower energy use than air-cooled alternatives. Many years
ago, the first water-cooled systems used potable water directly in the condenser to
provide heat rejection with the cooling water wasted to a drain. Cooling towers were
developed to recycle more than 98% of this water, resulting in tremendous reductions
in water and energy use as these systems grew in both size and popularity.
BY FRANK MORRISON, MEMBER ASHRAE
TECHNICAL FEATURE
PHOTO COURTESY OF NSCA (NATIONAL CENTER FOR SUPERCOMPUTING APPLICATIONS,
LOCATED ON THE CAMPUS OF THE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN)
Saving Energy With
Cooling Towers
*CTI Standard 201 has been replaced by two 2013 standards: STD 201-OM, Operations Manual for Thermal Performance Certification of Evaporative Heat Rejection Equipment and STD 201RS, Performance
Rating of Evaporative Heat Rejection Equipment.
This article was published in ASHRAE Journal, February 2014. Copyright 2014 ASHRAE. Posted at www.ashrae.org. This article may not be copied and/or
distributed electronically or in paper form without permission of ASHRAE. For more information about ASHRAE Journal, visit www.ashrae.org.
2. FEBRUARY 2014 ashrae.org A S H R A E J O U R N A L 35
TECHNICAL FEATURE
is above the low limit for almost all chillers). In prac-
tice, this lower limit varies and is dependent on the
type of chiller. The closer to full load the system runs,
the greater the energy savings from such strategies.
However, most chiller systems operate at less than full
load for the majority of time.
While it may seem counterintuitive, many designers
and operators have found that using less cooling tower
energy reduces overall system energy at many off-design
conditions. At such conditions, ancillary equipment
(condenser pumps and cooling tower fans) operating at
full design speed becomes a larger portion of the system
energy use, especially when variable speed chillers are
used. Reducing cooling tower fan speed can reduce asso-
ciated fan power significantly while increasing chiller
power only marginally. For example, slowing the tower
fan speed to 80% of design reduces tower fan power by
about half, while only raising the cooling tower leaving
water temperature about 3°F (1.7°C). Depending on the
specific load point, the increase in chiller energy con-
sumption from the higher condenser water temperature
may or may not be less than the reduction in cooling
tower energy. The key is to balance the performance
of the system components so overall performance is
optimized. Articles such as Taylor’s2,3,4 excellent series
on chilled water system design provide more details on
such strategies.
Closer Approach Selections
Another method to reduce system energy is to select a
cooling tower using a closer approach than might be typ-
ical for a particular area. The tower approach is defined
as the difference between the water temperature leav-
ing the cooling tower minus the entering wet-bulb
temperature. When a closer design approach is chosen,
the resulting cooling tower provides colder water to the
chiller condenser, even on a design day, which in turn
reduces compressor energy. This, of course, assumes the
system designer has not taken advantage of the colder
design water temperature to reduce the condenser sur-
face area of the chiller.
The added cooling tower cost and potentially greater
tower fan horsepower and pumping head must be evalu-
ated versus the expected chiller energy savings. Facilities
with constant year-round loads, such as those experi-
enced in data centers or certain manufacturing facilities,
typically derive the greatest benefit from this technique.
Fan Speed Control
There are several specific methods to optimize cool-
ing tower energy use. First, as required by Standard
90.1-2013, cooling tower fan speed must have the capa-
bility to be controlled proportional to the leaving fluid
temperature or condensing temperature/pressure.5
This can be accomplished in several ways, including
the use of two-speed motors or variable speed drive
technology. For multi-cell cooling towers, all of the
fans should be operated simultaneously at the same
fan speed, maximizing the heat transfer surface area
used in the evaporative cooling process, for the lowest
energy use. This is opposed to the traditional manner
of fan cycling (on/off) that provides step control (for
example, Tower 1 fan on, then Tower 2 fan on, etc., as
the load increases). This operating sequence becomes
even easier to apply today with the widespread use of
cost-effective variable speed drives (VSD), though the
sequence can also be used with either multi-speed or
pony motors.
To illustrate the potential energy savings, let’s
look at the case of a four-cell cooling tower with
and without variable speed fan drives as shown in
Photo 1. With full water flow over all cells, operat-
ing the fans in two cells at full speed with the fans
in the other two cells idle produces essentially the
same leaving water temperature off the tower as
when running the fans in all four cells at approxi-
mately 56% fan speed. However, by running all fans
simultaneously at the lower speed, the fan energy is
reduced by more than 60% compared to step control
PHOTO 1 Four cell crossflow open circuit cooling tower.
ABOUT THE AUTHOR Frank Morrison is manager, global strategy at Baltimore Aircoil Company
in Jessup, Md. He is chair of ASHRAE TC 3.6, Water Treatment, and a voting member of
ASHRAE SSPC 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings.
3. A S H R A E J O U R N A L ashrae.org FEBRUARY 201436
TECHNICAL FEATURE
thanks to the fan laws.† In addition to the significant
energy savings, this control sequence has other ben-
efits, including:
•• Significantly improved condenser water tempera-
ture control;
•• Fan system maintenance is minimized thanks to the
lower average fan speed and reduced starts and stops;
•• The cooling tower has a lower sound profile due to
the lower average fan speed coupled with the soft fan
starts and stops; and
•• All fan motors are regularly exercised without the
need for a lead/lag arrangement.
This simple energy-saving technique can be effec-
tively applied on both new and existing installations. Of
course, both the minimum fan speed and flow require-
ments for the specific cooling tower design must be fol-
lowed per the manufacturer’s recommendations.
Note that this fan control method for multi-cell cool-
ing towers and other heat rejection equipment has
been added as a requirement in Standard 90.1-2013
along with a 5% increase in the minimum efficiency
for axial fan, open circuit cooling towers. Additionally,
a limitation on the use of centrifugal fan, open circuit
cooling towers over approximately 300 nominal tons
(1318 kW) was incorporated in the 2010 edition of the
Standard helping to accelerate an important market
PHOTO 2 Multi-cell counterflow open circuit cooling tower installation.
†Assumes full design water flow over each cell in both cases; exact percentage savings will vary depending on the specific wet bulb, load conditions, and the estimation of the natural draft cooling capacity
of the two cells with the fans off.
Advertisement formerly in this space.
4. FEBRUARY 2014 ashrae.org A S H R A E J O U R N A L 37
TECHNICAL FEATURE
trend towards the use of cooling towers with lower
energy axial fans. It is important to note, however,
that centrifugal fan units can still be used on projects
under 300 nominal tons (1318 kW) and, without a size
restriction, on installations where unit sound attenu-
ation is required, when like-for-like replacements are
necessary, or for indoor ducted applications. The latter
is often used in colder climates or where building secu-
rity is an issue.
Lower Energy Cooling Towers
Another effective technique to reduce cooling tower
fan energy is to increase the amount of heat trans-
fer surface in the cooling tower thereby reducing the
required airflow and associated air pressure drop
through the tower. This, in turn, reduces the fan motor
size required for the same thermal duty. Motor size
reductions of 25% to 50% are often economically prac-
tical on many projects. The additional first cost of the
cooling tower, along with the larger support grillage, is
offset in part by lower fan motor wiring and VSD costs.
Depending on the specific model chosen, the tower
height may increase resulting in higher pumping costs,
but this is usually a relatively small factor and can be
minimized by the judicious selection of the cooling
tower. Combining all of these factors, the higher net
first cost is paid for by the large fan energy savings,
often producing a simple payback of two years or less.
These energy savings can also contribute toward earn-
ing LEED points for the building.
Tower Flow Turndown
After optimizing chiller and cooling tower fan
energy, designers and operators should then evalu-
ate condenser water flow turndown on open circuit
cooling towers as a further means for reducing sys-
tem energy use. Several important factors must be
considered. First, the fill in the cooling tower must
be properly wetted at all times to avoid wet/dry areas
that can lead to scaling in the fill pack. Scaling is the
accumulation of solids from the water at the wet/dry
interface. The amount of scaling depends on how well
the entire fill pack is wetted as well as the recirculat-
ing water quality in the cooling tower, which is mea-
sured by such indicators as the level of total dissolved
solids.
Uncontrolled scale can block both air and water
flow through the heat transfer media, which forces
the cooling tower fan to use more energy to meet
the design condenser water temperature setpoint.
Under high load conditions, this can also result in an
increase in chiller energy consumption or, if severe,
chiller surge. In addition, too low a flow over the
tower can result in winter icing issues, which will be
covered in more detail in the March issue in an article
by Paul Lindahl.
To avoid such issues, the minimum flow rate
over the cooling tower as specified by the manu-
facturer must be maintained, which may involve
shutting down some cells as chillers are cycled off.
Additionally, the cooling tower must be designed to
handle the expected flow turndown, which usually
involves features such as weir dams and/or a com-
bination of spray nozzles that can properly span the
expected range of water flows while providing ade-
quate wetting of the fill pack at all times. This applies
to whether a crossflow (Photo 1) or counterflow (Photo
2) design is specified. Crossflow towers typically use
gravity flow basins to distribute the cooling water over
the fill pack as shown in Figure 1, while counterflow
towers have pressurized water distribution systems
as shown in Figure 2. Similarly, the flow limits through
the condenser must also be checked as low velocities
below the manufacturer’s recommended minimum
can result in fouling of the condenser tubes. This
in turn increases system energy consumption by
increasing chiller energy use while forcing the cool-
ing tower to work harder to meet the necessary con-
denser water temperature that is being called for by
the system.
Second, a portion of the pumping head on an open
circuit cooling tower is fixed, which lowers the poten-
tial pump energy savings compared to those that are
achievable with closed loop systems such as the chilled
water piping or a closed condenser loop that uses a
closed circuit cooling tower. Though important, these
factors typically place condenser pump savings last
in line after the chiller, cooling tower fan, and chilled
water pump. Thus the designer and operator must
evaluate the potential energy savings of reducing the
water flow over the cooling tower with the operating
risk to the system. These cautions apply whether the
system uses 2.0 gpm/ton or 3.0 gpm/ton (0.036 L/s∙kW
to 0.054 L/s∙kW) on the condenser loop. While in many
cases the system energy is reduced with the lower
condenser design flow,6 note that there is even less
5. A S H R A E J O U R N A L ashrae.org FEBRUARY 201438
TECHNICAL FEATURE
increasing approach temperature at lower wet bulbs
results in a cooling tower selection that is oversized for
the summer duty.
Since many computer facilities are lightly loaded
during their first few years of operation, system
control can suffer, which is a serious concern for
computer system operators due to their need for
high reliability and system uptime in such facili-
ties. To reduce the oversizing, the switchover design
temperature requirement for full economization
was revised from a single fixed design temperature
for all computer rooms (wet bulb for cooling towers
and dry bulb for dry coolers) to one that varies by
climate zone. The lower design temperature reduces
the size of the heat rejection device required for the
water economizer which in turn reduces first cost
as well as improves system control under low load
conditions.
Closed Circuit Cooling Towers and Evaporative Condensers
While this article primarily discussed open circuit
cooling towers, the fan speed control requirements
mentioned earlier also apply to closed circuit cooling
towers, evaporative condensers, dry coolers, and air
cooled condensers. Minimum efficiencies and thermal
performance certification requirements for closed cir-
cuit cooling towers were added in the 2010 edition of
Standard 90.1. Closed circuit cooling towers combine
the function of a cooling tower and heat exchanger in
one compact device, keeping the process fluid clean in
a closed loop.
potential condenser pump energy savings to capture,
which further alters the risk/reward ratio.
Standard 90.1-2013 now requires that all open cir-
cuit cooling towers on water-cooled chiller systems
with either multiple or variable speed condenser
water pumps have the capability of a minimum 50%
flow turndown. Note, however, that there are no
requirements or guidelines for implementing con-
denser flow turndown in the standard at this time
as each system is unique. As such, system design-
ers and operators should consult with their chiller
and tower manufacturer for specific flow turndown
recommendations for their system. As mentioned
previously, the local makeup water quality, the
expected water treatment program, and the sophis-
tication of the control system required should also
be evaluated.
Water Economizers for Computer Rooms
January’s article by Mick Schwedler7 covered the
proper application of water economizers, cautioning
the reader to properly account for the changes in cool-
ing tower approach temperature at lower wet-bulb
temperatures. Reflecting this same phenomenon, a
change to the requirements for water economizers that
are primarily used for computer room applications was
implemented in Standard 90.1-2013. Unlike a comfort
cooling application where the load decreases in winter,
the load in a typical computer room remains relatively
constant throughout the year, independent of climate
variations. The high year-round load coupled with the
FIGURE 2 Induced draft, axial fan, counterflow open circuit cooling tower.
Hot Water In
Air In
Cooled Water Out
Air In
Fill SurfaceWater
Warm Air Out
Drift Eliminators
Typical on All Four Sides
FIGURE 1 Induced draft, axial fan, crossflow open circuit cooling tower.
Hot Water In
Air In
Cooled Water Out
Fill
Surface
Warm Air Out
Air In
Air Inlet
Louvers
Water Water
Hot Water In
Warm
Air
Warm
Air
Cold Water Basin
7. A S H R A E J O U R N A L ashrae.org FEBRUARY 201440
TECHNICAL FEATURE
PHOTO 3 Regular cooling tower maintenance pays off.
Furthermore, minimum efficien-
cies for evaporative condensers used
in both ammonia and halocarbon
applications have been added with
the 2013 edition. Evaporative con-
densers are similar to closed circuit
cooling towers except that a refrig-
erant is condensed within the coil.
Evaporative condensers are often
used in cold storage warehouses,
food processing facilities, supermar-
kets, industrial processes, and, to a
limited extent, HVAC systems.
Maintenance Benefits
Finally, no matter what the specific system design,
paying regular attention to the cooling tower (along with
other system components) through a comprehensive
maintenance and water treatment program can save
time, money, and energy while increasing the cooling
tower’s life expectancy. Owners and
operators with a working knowl-
edge of cooling tower preventive
maintenance and upgrade tech-
nology can also take advantage of
cost-saving ideas and procedures,8
such as replacement fill kits or the
more energy efficient operating
sequences described earlier. Be
sure to refer to the cooling tower’s
operating and maintenance manual
for the appropriate maintenance
requirements and service intervals.
In addition, the article on cooling
tower maintenance in the Bibliography is a good source
of best practices that can be used to keep your cooling
towers operating at peak efficiency.
Conclusion
Water-cooled systems save energy compared to air
cooled alternatives for cooling duties. Proper selec-
tion, design, operation, and maintenance of evapora-
tive heat rejection equipment used in such systems
offer the opportunity to further optimize system
energy usage. Evaluating sub-system and system
performance, as opposed to the performance of indi-
vidual system components, is a path to significantly
improve overall building performance. This energy
saving opportunity will be explored by SSPC 90.1 as
the Committee begins development of the 2016 edi-
tion of Standard 90.1.
References
1. Path B water cooler chiller per Richard Lord, Carrier Corporation
and Vice Chair, SSPC 90.1.
2. Taylor, S. 2011. “Optimizing Design and Control of Chilled Water
Systems—Part 2: Condenser Water System Design” ASHRAEJournal
53(9):26.
3. Taylor, S. 2012. “Optimizing Design and Control of Chilled Water
Systems—Part 4: Chiller & Cooling Tower Selection.” ASHRAE
Journal 54 (4):60.
4. Taylor, S. 2012. “Optimizing Design and Control of Chilled Water
Systems—Part 5: Optimized Control Sequences.” ASHRAE Journal
54(6):56.
5. ANSI/ASHRAE/IES Standard 90.1-2013, Energy Standard for Buildings
Except Low-Rise Residential Buildings, Paragraph 6.5.5.2.
6. Copeland, C.C. 2012. “Improving Energy Performance of NYC’s
Existing Office Buildings.” ASHRAE Journal 54(8):38.
7. Schwedler,M.2014.“EffectofHeatRejectionLoadandWetBulbon
Cooling Tower Performance.” ASHRAE Journal 56(1):16.
8. Babcock, G. 2005. “Because temperature matters: maintaining
cooling towers.” ASHRAE Journal 47(3):51.
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