Analysis of Heat Transfer in Spiral Plate Heat Exchanger Using Experimental a...ijsrd.com
Heat transfer is the key to several processes in industrial application. In a present days maximum efficient heat transfer equipment are in demand due to increasing energy cost. For achieving maximum heat transfer, the engineers are continuously upgrading their knowledge and skills by their past experience. Present work is a skip in the direction of demonstrating the use of the computational technique as a tool to substitute experimental techniques. For this purpose an experimental set up has been designed and developed. Analysis of heat transfer in spiral plate heat exchanger is performed and same Analysis of heat transfer in spiral plate heat exchanger can be done by commercially procurable computational fluid dynamic (CFD) using ANSYS CFX and validated based on this forecasting. Analysis has been carried out in parallel and counter flow with inward and outward direction for achieving maximum possible heat transfer. In this problem of heat transfer involved the condition where Reynolds number again and again varies as the fluid traverses inside the section of flow from inlet to exit, mass flow rate of working fluid is been modified with time. By more and more analysis and experimentation and systematic data degradation leads to the conclusion that the maximum heat transfer rates is obtained in case of the inward parallel flow configuration compared to all other counterparts, which observed to vary with small difference in each section. Furthermore, for the increase heat transfer rate in spiral plate heat exchanger is obtain by cascading system.
This presentation is on shell and tube heat exchanger in which its design parameters and its troubleshooting conditions designed for better understanding and learning of all
Analysis of Heat Transfer in Spiral Plate Heat Exchanger Using Experimental a...ijsrd.com
Heat transfer is the key to several processes in industrial application. In a present days maximum efficient heat transfer equipment are in demand due to increasing energy cost. For achieving maximum heat transfer, the engineers are continuously upgrading their knowledge and skills by their past experience. Present work is a skip in the direction of demonstrating the use of the computational technique as a tool to substitute experimental techniques. For this purpose an experimental set up has been designed and developed. Analysis of heat transfer in spiral plate heat exchanger is performed and same Analysis of heat transfer in spiral plate heat exchanger can be done by commercially procurable computational fluid dynamic (CFD) using ANSYS CFX and validated based on this forecasting. Analysis has been carried out in parallel and counter flow with inward and outward direction for achieving maximum possible heat transfer. In this problem of heat transfer involved the condition where Reynolds number again and again varies as the fluid traverses inside the section of flow from inlet to exit, mass flow rate of working fluid is been modified with time. By more and more analysis and experimentation and systematic data degradation leads to the conclusion that the maximum heat transfer rates is obtained in case of the inward parallel flow configuration compared to all other counterparts, which observed to vary with small difference in each section. Furthermore, for the increase heat transfer rate in spiral plate heat exchanger is obtain by cascading system.
This presentation is on shell and tube heat exchanger in which its design parameters and its troubleshooting conditions designed for better understanding and learning of all
HEAT EXCHANGERS. Heat exchangers are devices that facilitate the exchange of heat between two fluids that are at different temperature while keeping them from mixing with each other.
2. Double Pipe Heat Exchangers
3. A typical double pipe heat exchanger basically consists of a tube or pipe fixed concentrically inside a larger pipe or tube They are used when flow rates of the fluids and the heat duty are small (less than 5 kW) These are simple to construct, but may require a lot of physical space to achieve the desired heat transfer area.
4. Double-pipe exchangers is the generic term covering a range of jacketed 'U' tube exchangers normally operating in countercurrent flow of two types which is true double pipes and multitubular hairpins. One fluid flows through the smaller pipe while the other fluid flows through the annular space between the two pipes. Two types of flow arrangement: Parallel flow Counter flow
5. • The fluids may be separated by a plane wall but more commonly by a concentric tube (double pipe) arrangement shown in fig. If both the fluids move in the same direction, the arrangement is called a parallel flow type. In the counter flow arrangement the fluids move in parallel but opposite directions. In a double pipe heat exchanger, either the hot or cold fluid occupies the annular space and the other fluid moves through the inner pipe. The method of solving the problem using logarithmic mean temperature difference is typical and more iteration must be done. So it takes more time for the problem to solve. Therefore another method is practiced for solving this type of problems. This method is known as Effectiveness and Number of Transfer Units or simply ε-NTU method.“Effectiveness of heat exchangers is defined as actual heat transfer rate by maximum possible heat transfer rate”.The LMTD method may be applied to design problems for which the fluid flow rates and inlet temperatures, as well as a desired outlet temperature, are prescribed.
6. Application of Double Pipe Heat Exchanger Pasteurization or sterilization of food and bioproducts Condensers and evaporators of air conditioners Radiators for internal combustion engines Charge air coolers and intercoolers for cooling supercharged engine intake air of diesel engines.
Heat Exchanger (Shell and tubes) by sujan kharel..ansaluniversity3
Hey! This is the best presentation about Heat exchanger device of shell and tubes type and there is also mentioned their defects and overcome method...
Condensers and evaporators are basically heat exchangers in which the refrigerant undergoes a phase change. Next to compressors, proper design and selection of condensers and evaporators is very important for satisfactory performance of any refrigeration system.
An experimental investigation of annular fins under forced convectioneSAT Journals
Abstract
Heat transfer characteristics under forced convection are investigated experimentally by varying parameters like surface area,
base-to-ambient temperature difference and Reynolds number. To investigate the performance of fins experimentally, fins made of
aluminium (high thermal conductivity) are taken. For varying the surface area fin with 11 mm diameter without circumferential
fins, fin with 31 mm diameter and annular fins of 31 mm diameter are taken as specimens. Base to ambient temperature difference
is varied with the aid of dimmerstat ranging from 25W to 45W. Reynolds number is also varied by varying the velocities of air.
Velocities are varied by the aid of fan. Then these fins are tested under different load conditions, different Reynolds number by
varying the surface area of fins increase the rate of heat transfer. With the variation of relevant parameters under forced
convection heat transfer rates are analyzed experimentally. Experiments are conducted by using the annular fins, fin with
diameter 11mm without circumferential fins and fin with diameter 31mm at different Reynolds number and loads under forced
convection and comparison is made between fins. Experimental results shows that forced convection heat transfer rate from fins
depend on surface areas, base ambient temperature difference and Reynolds number. The base temperature for annular fins is
reduced by 30% when compared to fin with diameter 11mm due to increase in surface area about 40%. The base temperature for
annular fins is reduced by 10% when compared to fin with diameter of 31mm due to decrease in surface area about 41%. It is
also observed that at higher heat load i.e., 45W, the overall fin efficiency of annular fins is increased by 44% and 8% compared to
fin with diameter of 11mm and 31mm respectively. At higher Reynolds number range 800-2000, heat transfer rate increases in
annular fins due to more number of air molecules get in contact with the heated surface
HEAT EXCHANGERS. Heat exchangers are devices that facilitate the exchange of heat between two fluids that are at different temperature while keeping them from mixing with each other.
2. Double Pipe Heat Exchangers
3. A typical double pipe heat exchanger basically consists of a tube or pipe fixed concentrically inside a larger pipe or tube They are used when flow rates of the fluids and the heat duty are small (less than 5 kW) These are simple to construct, but may require a lot of physical space to achieve the desired heat transfer area.
4. Double-pipe exchangers is the generic term covering a range of jacketed 'U' tube exchangers normally operating in countercurrent flow of two types which is true double pipes and multitubular hairpins. One fluid flows through the smaller pipe while the other fluid flows through the annular space between the two pipes. Two types of flow arrangement: Parallel flow Counter flow
5. • The fluids may be separated by a plane wall but more commonly by a concentric tube (double pipe) arrangement shown in fig. If both the fluids move in the same direction, the arrangement is called a parallel flow type. In the counter flow arrangement the fluids move in parallel but opposite directions. In a double pipe heat exchanger, either the hot or cold fluid occupies the annular space and the other fluid moves through the inner pipe. The method of solving the problem using logarithmic mean temperature difference is typical and more iteration must be done. So it takes more time for the problem to solve. Therefore another method is practiced for solving this type of problems. This method is known as Effectiveness and Number of Transfer Units or simply ε-NTU method.“Effectiveness of heat exchangers is defined as actual heat transfer rate by maximum possible heat transfer rate”.The LMTD method may be applied to design problems for which the fluid flow rates and inlet temperatures, as well as a desired outlet temperature, are prescribed.
6. Application of Double Pipe Heat Exchanger Pasteurization or sterilization of food and bioproducts Condensers and evaporators of air conditioners Radiators for internal combustion engines Charge air coolers and intercoolers for cooling supercharged engine intake air of diesel engines.
Heat Exchanger (Shell and tubes) by sujan kharel..ansaluniversity3
Hey! This is the best presentation about Heat exchanger device of shell and tubes type and there is also mentioned their defects and overcome method...
Condensers and evaporators are basically heat exchangers in which the refrigerant undergoes a phase change. Next to compressors, proper design and selection of condensers and evaporators is very important for satisfactory performance of any refrigeration system.
An experimental investigation of annular fins under forced convectioneSAT Journals
Abstract
Heat transfer characteristics under forced convection are investigated experimentally by varying parameters like surface area,
base-to-ambient temperature difference and Reynolds number. To investigate the performance of fins experimentally, fins made of
aluminium (high thermal conductivity) are taken. For varying the surface area fin with 11 mm diameter without circumferential
fins, fin with 31 mm diameter and annular fins of 31 mm diameter are taken as specimens. Base to ambient temperature difference
is varied with the aid of dimmerstat ranging from 25W to 45W. Reynolds number is also varied by varying the velocities of air.
Velocities are varied by the aid of fan. Then these fins are tested under different load conditions, different Reynolds number by
varying the surface area of fins increase the rate of heat transfer. With the variation of relevant parameters under forced
convection heat transfer rates are analyzed experimentally. Experiments are conducted by using the annular fins, fin with
diameter 11mm without circumferential fins and fin with diameter 31mm at different Reynolds number and loads under forced
convection and comparison is made between fins. Experimental results shows that forced convection heat transfer rate from fins
depend on surface areas, base ambient temperature difference and Reynolds number. The base temperature for annular fins is
reduced by 30% when compared to fin with diameter 11mm due to increase in surface area about 40%. The base temperature for
annular fins is reduced by 10% when compared to fin with diameter of 31mm due to decrease in surface area about 41%. It is
also observed that at higher heat load i.e., 45W, the overall fin efficiency of annular fins is increased by 44% and 8% compared to
fin with diameter of 11mm and 31mm respectively. At higher Reynolds number range 800-2000, heat transfer rate increases in
annular fins due to more number of air molecules get in contact with the heated surface
Power Plant Regenerative feed heating and design aspects of Feed Heaters.This is a ppt for beginners in Power Plant Engineering.Also discusses Heat Transfer and Rankine cycle.
this ppt is made with the reference of heat exchangers that have been used in NHFI, it almost covers their every aspect that is their working, maintenance, and safety !!
so please suit yourself!!!
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.
• Types of heat exchangers
• Classification of heat exchangers
• components of heat exchanger
• Materials of heat exchanger
• troubleshooting of heat exchanger
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
2. Coolers and heaters are heatCoolers and heaters are heat
exchangers and they transfer heatexchangers and they transfer heat
energy from one medium to another.energy from one medium to another.
Consist of two channels or system ofConsist of two channels or system of
channels, one for each medium.channels, one for each medium.
Mediums are separated by partitionsMediums are separated by partitions
through which heat is transferred fromthrough which heat is transferred from
the warmer to the cooler one. Heat canthe warmer to the cooler one. Heat can
only flow from a higher heat source to aonly flow from a higher heat source to a
lower heat region.lower heat region.
3. Heat exchangers are called by variousHeat exchangers are called by various
names such as coolers, heaters,names such as coolers, heaters,
condensers and evaporators. The freshcondensers and evaporators. The fresh
water coolers, fuel oil heaters, lubricatingwater coolers, fuel oil heaters, lubricating
oil coolers, air coolers are just some of theoil coolers, air coolers are just some of the
heat exchangers found on board ships.heat exchangers found on board ships.
4. CoolersCoolers
On board ships, the main engine is cooledOn board ships, the main engine is cooled
by the jacket cooling water and lubricatingby the jacket cooling water and lubricating
oil. These fluids are then passed throughoil. These fluids are then passed through
a cooler where sea water is used as thea cooler where sea water is used as the
cooling medium to cool the fresh watercooling medium to cool the fresh water
and the lubricating oil. After being cooledand the lubricating oil. After being cooled
the fluids return back to the main enginethe fluids return back to the main engine
and the sea water is dischargedand the sea water is discharged
overboard.overboard.
5. HeatersHeaters
Heaters are used for various purposes onHeaters are used for various purposes on
board ships. The most essential one isboard ships. The most essential one is
used for the fuel oil heating. Theused for the fuel oil heating. The
temperature of the fuel oil is raised bytemperature of the fuel oil is raised by
passing steam through the heating tubespassing steam through the heating tubes
and the oil on the outside of these tubes.and the oil on the outside of these tubes.
Thus heat is transferred from the steam toThus heat is transferred from the steam to
the fuel oil.the fuel oil.
6. Types of Heat ExchangersTypes of Heat Exchangers
In theIn the shell & tube typeshell & tube type heat exchangerheat exchanger
one medium flows through a set of tubesone medium flows through a set of tubes
and the other medium flows on theand the other medium flows on the
outside. Thus heat transfer take placeoutside. Thus heat transfer take place
across the tube walls.across the tube walls.
In theIn the plate typeplate type heat exchanger, a setheat exchanger, a set
of corrugated plates are tightly packedof corrugated plates are tightly packed
with spaces in between. The differentwith spaces in between. The different
mediums flow on either sides of the platemediums flow on either sides of the plate
and heat transfer takes place across theand heat transfer takes place across the
plate.plate.
7. Tubular exchangers are used in greatTubular exchangers are used in great
numbers, far more than any other type ofnumbers, far more than any other type of
exchanger. They are made in a wideexchanger. They are made in a wide
variety of sizes and styles.variety of sizes and styles.
Tubular exchangers are so widely usedTubular exchangers are so widely used
because the technology is wellbecause the technology is well
established for making precision metalestablished for making precision metal
tubes capable of containing hightubes capable of containing high
pressures in a variety of materials. Therepressures in a variety of materials. There
is virtually no limit to the range ofis virtually no limit to the range of
pressures and temperatures that can bepressures and temperatures that can be
accommodated.accommodated.
8. 1.1. Liquid/liquidLiquid/liquid.. This is by far the mostThis is by far the most
common application of tubularcommon application of tubular
exchangers. Typically, cooling water onexchangers. Typically, cooling water on
one side is used to cool a hot effluentone side is used to cool a hot effluent
stream. Both fluids are pumped throughstream. Both fluids are pumped through
the exchanger so that the principal modethe exchanger so that the principal mode
of heat transfer is forced convective heatof heat transfer is forced convective heat
transfer.transfer.
9. 2.2. Liquid/gasLiquid/gas.. This is also very common,This is also very common,
typically for the air cooling of a hot liquidtypically for the air cooling of a hot liquid
effluent. The liquid is pumped through theeffluent. The liquid is pumped through the
tubes with very high rates of convectivetubes with very high rates of convective
heat transfer. The air, in cross-flow overheat transfer. The air, in cross-flow over
the tubes, may be in the forced or freethe tubes, may be in the forced or free
convective mode. Heat-transferconvective mode. Heat-transfer
coefficients on the air side are lowcoefficients on the air side are low
compared with those on the liquid side.compared with those on the liquid side.
Fins are usually added on the outsides (airFins are usually added on the outsides (air
side) of the tubes to compensate.side) of the tubes to compensate.
10. 3.3. Gas/gasGas/gas.. This type of exchanger isThis type of exchanger is
found in the exhaust-gas/air preheating,found in the exhaust-gas/air preheating,
steel furnaces, and etc. Insteel furnaces, and etc. In many casesmany cases
one gas is compressed so the density isone gas is compressed so the density is
high, while the other is at low pressurehigh, while the other is at low pressure
with a low density. Normally the high-with a low density. Normally the high-
density fluid flows inside the tubes.density fluid flows inside the tubes.
Internal and external fins are sometimesInternal and external fins are sometimes
provided to enhance the heat transfer.provided to enhance the heat transfer.
11. 4.4. Condensers.Condensers. These may be liquidThese may be liquid
(water) or gas (air) cooled. Alternatively,(water) or gas (air) cooled. Alternatively,
the heat from condensing steams may bethe heat from condensing steams may be
used to heat another processing fluid.used to heat another processing fluid.
Normally the condensing fluid is routed inNormally the condensing fluid is routed in
either of two ways:either of two ways:
12. a.a. Outside the tubes with liquid cooling,Outside the tubes with liquid cooling,
i.e., a water-cooled steam condenser. Finsi.e., a water-cooled steam condenser. Fins
are not necessary either inside or outsideare not necessary either inside or outside
the tubes.the tubes.
b.b. Inside the tubes with gas cooling, i.e.,Inside the tubes with gas cooling, i.e.,
an air-cooled Freon condenser heat pumpan air-cooled Freon condenser heat pump
or refrigerating system. Fins are normallyor refrigerating system. Fins are normally
provided on the outsides of the tubes.provided on the outsides of the tubes.
The tubes may be flattened to obtain aThe tubes may be flattened to obtain a
better ratio of surface area to flow crossbetter ratio of surface area to flow cross
13. 5.5. Evaporators and boilersEvaporators and boilers
a. Fired systems,a. Fired systems, in which the combustionin which the combustion
of fuels at very high temperatures butof fuels at very high temperatures but
ambient pressure (and low density)ambient pressure (and low density)
generate steam under pressure. Normallygenerate steam under pressure. Normally
the water and/or steam is contain insidethe water and/or steam is contain inside
the tubes (water tube boiler), and pin fins,the tubes (water tube boiler), and pin fins,
studs, or some other form of extendedstuds, or some other form of extended
surface is applied to the tubes to enhancesurface is applied to the tubes to enhance
the heat transfer. In smaller systems thethe heat transfer. In smaller systems the
combustion products may pass throughcombustion products may pass through
the tubes (fire tube boilers).the tubes (fire tube boilers).
14. b. Unfired systems.b. Unfired systems. These embrace aThese embrace a
great variety of different boiler andgreat variety of different boiler and
evaporator heat exchangers. Manyevaporator heat exchangers. Many
chemical and food-processing applicationschemical and food-processing applications
involve the use ofinvolve the use of steamsteam oror electricelectric
heating to evaporate solvents, concentrateheating to evaporate solvents, concentrate
solutions, distill liquors, or dehydratesolutions, distill liquors, or dehydrate
compounds.compounds.
15. Type of Flow and Flow Patterns inType of Flow and Flow Patterns in
HeatHeat
Laminar FlowLaminar Flow
17. Flow ArrangementsFlow Arrangements
Parallel Flow PatternParallel Flow Pattern
In this type, both the hot andIn this type, both the hot and
thethe
cold fluids flow in the samecold fluids flow in the same
direction.direction.
This type is not normally usedThis type is not normally used
inin
marine practice except incasesmarine practice except incases
where a combination of thewhere a combination of the
basic flow arrangement is used.basic flow arrangement is used.
This is due to its inherentThis is due to its inherent
poorer heat transfer rates.poorer heat transfer rates.
Advantages –Advantages –
a) lower heat transfer surfacea) lower heat transfer surface
temperature.temperature.
b) more even heat transferb) more even heat transfer
18. Contra or Counter Flow PatternContra or Counter Flow Pattern
This arrangement is widelyThis arrangement is widely
used but the use of baffles orused but the use of baffles or
multi-passes of coolant upsetmulti-passes of coolant upset
the basic flow arrangement sothe basic flow arrangement so
that in most cases athat in most cases a
combination of all three iscombination of all three is
used.used.
Plate type of heat exchangerPlate type of heat exchanger
can use this arrangementcan use this arrangement
without combination with anywithout combination with any
other.other.
Advantages –Advantages –
a) best heat transfer rates.a) best heat transfer rates.
b) closer temperatureb) closer temperature
differential.differential.
c) outlet temperature of coolantc) outlet temperature of coolant
can be higher than outletcan be higher than outlet
temperature of hot fluidtemperature of hot fluid
19. Cross Flow PatternCross Flow Pattern
Exchangers such as airExchangers such as air
coolers for dieselcoolers for diesel
engines, super-heatersengines, super-heaters
or tubular gas heaters inor tubular gas heaters in
boilers use thisboilers use this
arrangement but again itarrangement but again it
is usual to find that theis usual to find that the
heat basic flow isheat basic flow is
complicated by multi-complicated by multi-
passes and the result ispasses and the result is
a combination of flowa combination of flow
arrangements.arrangements.