An energy audit is a systematic process of evaluating and analyzing energy usage in a building, facility, or industrial process to identify opportunities for energy efficiency improvements, cost savings, and environmental sustainability. The goal of an energy audit is to assess energy consumption patterns, identify areas of inefficiency or waste, and recommend measures to optimize energy usage and reduce overall energy consumption. Here's an overview of the typical steps involved in conducting an energy audit: 1. **Pre-Audit Planning:** Define the scope and objectives of the energy audit, including the areas or systems to be evaluated, the level of detail required, and the desired outcomes. Identify key stakeholders, establish audit goals, and gather relevant documentation, such as utility bills, building plans, and equipment specifications. 2. **Data Collection and Analysis:** Collect comprehensive data on energy consumption, including utility bills, meter readings, and operational data

1. Energy Auditing &
Management
Topic: Electric loads of air conditioning and
refrigeration-energy conservation
measures-cool storage-optimal operation-
case study

2. What is Refrigeration and Air Conditioning
 Refrigeration and air conditioning is used to cool products or a building
environment.
 The refrigeration or air conditioning system transfers heat from a cooler
low-energy reservoir to a warmer high-energy reservoir.

3. Heat transfer loop in Refrigeration System

4. Operation of Refrigeration System
There are several heat transfer loops in a refrigeration system as
shown in Figure 2.
Thermal energy moves from left to right as it is extracted from
the space and expelled into the outdoors through five loops of
heat transfer:
1). Indoor air loop: In the left loop, indoor air is driven by the
supply air fan through a cooling coil, where it transfers its heat
to chilled water. The cool air then cools the building space.
2). Chilled water loop: Driven by the chilled water pump,
water returns from the cooling coil to the chiller’s evaporator to
be re-cooled.

5. Operation of Refrigeration System
3). Refrigerant loop: Using a phase-change refrigerant,
the chiller’s compressor pumps heat from the chilled water
to the condenser water.
4). Condenser water loop: Water absorbs heat from the
chiller’s condenser, and the condenser water pump sends it
to the cooling tower.
5. Cooling tower loop: The cooling tower’s fan drives air
across an open flow of the hot condenser water,
transferring the heat to the outdoors.

6. Types of Refrigeration and Air Conditioning
 1). Vapour Compression Refrigeration System
 The refrigeration cycle is shown in fig. and can be broken
down into the following stages:
 1–2.Low-pressure liquid refrigerant in the evaporator
absorbs heat from its surroundings, usually air, water or
some other process liquid. During this process it changes
its state from a liquid to a gas, and at the evaporator exit
is slightly superheated.
 2–3.The superheated vapour enters the compressor where
its pressure is raised. The temperature will also increase,
because a proportion of the energy put into the
compression process is transferred to the refrigerant.

7. Vapour Compression Refrigeration System(Cont.)
3-4. The high pressure superheated gas passes from the compressor
into the condenser. The initial part of the cooling process (3-3a) de-
superheats the gas before it is then turned back into liquid (3a-3b).
The cooling for this process is usually achieved by using air or
water. A further reduction in temperature happens in the pipe work
and liquid receiver (3b-4), so that the refrigerant liquid is sub-
cooled as it enters the expansion device.

8.  4-1 The high-pressure sub-cooled liquid passes through the
expansion device, which both reduces its pressure and controls
flow into the evaporator.
Vapour Compression Refrigeration System(Cont.)

9. 2. Vapour Absorption Refrigeration System
 Evaporator: The refrigerant (water) evaporates at around 4 degree C under a high
vacuum condition of 754 mm Hg in the evaporator. Chilled water goes through heat
exchanger tubes in the evaporator and transfers heat to the evaporated refrigerant.

10. Vapour Absorption Refrigeration System(Cont.)
 The evaporated refrigerant (vapor) turns into liquid again, while the
latent heat from this vaporization process cools the chilled water (in
the diagram from 12 degree C to 7 degree C). The chilled water is then
used for cooling purposes.

11. Vapour Absorption Refrigeration System(Cont.)
 Absorber: In order to keep evaporating, the refrigerant vapor
must be discharged from the evaporator and refrigerant (water)
must be supplied. The refrigerant vapor is absorbed into lithium
bromide solution, which is convenient to absorb the refrigerant
vapor in the absorber. The heat generated in the absorption
process is continuously removed from the system by cooling
water. The absorption also maintains the vacuum inside the
evaporator.
 High Pressure Generator: As lithium bromide solution is
diluted, the ability to absorb the refrigerant vapor reduces. In
order to keep the absorption process going, the diluted lithium
bromide solution must be concentrated again.

12. Vapour Absorption Refrigeration System(Cont.)
 An absorption chiller is provided with a solution concentrating system,
called a generator. Heating media such as steam, hot water, gas or oil
perform the function of concentrating solutions.
Condenser:- To complete the refrigeration cycle, and thereby
ensuring the refrigeration takes place continuously, the following two
functions are required:

13. Vapour Absorption Refrigeration System(Cont.)
1. To concentrate and liquefy the evaporated refrigerant vapour, which is
generated in the High pressures generator.
2. To supply the condensed water to the evaporator as refrigerant (water)
For these two functions a condenser is installed.

14. Energy Efficiency Opportunities
1)Optimization of Process Heat Exchangers: There is a tendency to apply
high safety margins to operations, which the compressor suction pressure /
evaporator set point. For instance, a process-cooling requirement of 15 oC
would need chilled water at a lower temperature, but the range can vary from
6 oC to about 10 oC. At chilled water of 10 oC, the refrigerant side
temperature has to be lower (about –5 oC to +5oC). The refrigerant
temperature determines the corresponding suction pressure of the refrigerant,
which in turn determines the inlet duty conditions for the refrigerant
compressor. Applying the optimum / minimum driving force (temperature
difference) can thus help to reach the highest possible suction pressure at the
compressor, thereby minimizing energy consumption

15. Energy Efficiency Opportunities(Cont.)
2)Maintenance of Heat Exchanger: Surfaces Once compressors
have been purchased, effective maintenance is the key to
optimizing power consumption. Heat transfer can also be improved
by ensuring proper separation of the lubricating oil and the
refrigerant, timely defrosting of coils, and increasing the velocity
of the secondary coolant (air, water, etc.). However, increased
velocity results in larger pressure drops in the distribution system
and higher power consumption in pumps / fans. Therefore, careful
analysis is required to determine the optimum velocity.

16. Energy Efficiency Opportunities(Cont.)
3)Multi-Staging For Efficiency: Efficient compressor operation
requires that the compression ratio be kept low, to reduce discharge
pressure and temperature. For low temperature applications
involving high compression ratios, and for wide temperature range
requirements, it is preferable (due to equipment design limitations)
and often economical to employ multi-stage reciprocating machines
or centrifugal / screw compressors. There are two types of multi-
staging systems, which are applicable to all types of compressors:
compound and cascade. With reciprocating or rotary compressors,
two-stage compressors are preferable for load temperatures from –
20 degree C to –58 degree C, and with centrifugal machines for
temperatures around – 43 degree C.

17. Energy Efficiency Opportunities(Cont.)
 System Design Features: In overall plant design, adoption of good practices
improves the energy efficiency significantly. Some areas for consideration are:
 Design of cooling towers with FRP impellers and film fills, PVC drift eliminators,
etc. • Use of softened water for condensers in place of raw water.
 Use of economic insulation thickness on cold lines, heat exchangers, considering
cost of heat gains and adopting practices like infrared thermography for monitoring -
applicable especially in large chemical / fertilizer / process industry.
 Adoption of roof coatings / cooling systems, false ceilings / as applicable, to
minimize refrigeration load.
 Adoption of energy efficient heat recovery devices like air to air heat exchangers to
precool the fresh air by indirect heat exchange; control of relative humidity through
indirect heat exchange rather than use of duct heaters after chilling.

18. Cold Storage
Cold storage is the storage of any temperature-controlled
substance that prevents that substance from decaying or
not adhering to laws and regulations that apply to that
item.
Energy efficiency leads to another cost-related concern.
Studies have shown that refrigerated warehouses and cold
storage facilities can be incredibly inefficient if they aren’t
equipped with the highest quality doors and insulation, and
if the warehousing process isn’t optimized to limit
exposure of the open warehouse to the outside world.

19. Types Of Cold Storage
1)Refrigerated Containers: Refrigerated containers are the
most basic and often the most cost-effective option for cold
storage of small quantities of temperature sensitive products.
They can also be mobile, which gives them the advantage of
extra flexibility.
2)Blast Freezers And Chillers: Blast freezers and chillers
are ideal for companies who need to quickly cool and store
food before it reaches its end consumer. It’s common for
some larger restaurants and catering companies to use them.
3)Cold Rooms: Cold rooms are exactly what they sound like.
They are a larger alternative to the options listed above.

20. Types Of Cold Storage
4)Pharmaceutical Grade Cold Storage: Hospitals and
research institutions may make use of pharmaceutical
grade cold storage units. These units are equipped with
extra features that make them ideal for
biopharmaceuticals, blood, and certain vaccines.
5)Plant-Attached Cold Storage: Plant attached cold
storage is the preferred option for some manufacturers
who want to keep their cold storage in house. Products can
be transported via conveyor straight from manufacturing
to a dedicated cold storage facility on-site.

21. Case Study
 Initial Situation:
• Total electricity consumption for AC and refrigeration systems:
100,000 kWh per month
• Cost of electricity: $0.12 per kWh
• Assume an average efficiency of 8 Seasonal Energy Efficiency Ratio
for the existing systems
 Energy Conservation Measures Implemented:
1. Upgrading to newer, more efficient systems with an average SEER of
15.
2. Implementing smart thermostats and controls.
3. Installing VFDs to optimize energy usage.
4. Incorporating occupancy sensors.

22. Case Study(Cont.)
 Calculation:
1. Energy Efficiency Improvement due to Upgrades:
1. Initial SEER: 8
2. New SEER: 15
3. Energy savings percentage = ((New SEER - Initial SEER) / New SEER) * 100
4. Energy savings percentage = ((15 - 8) / 15) * 100 = 46.67%
2. Total energy savings due to improved efficiency = 100,000 kWh * 46.67% = 46,670
kWh per month
3. Savings from Smart Controls, VFDs, and Occupancy Sensors:
1. These measures collectively aim to reduce energy wastage during unoccupied
hours and optimize usage.
2. Assuming an additional 10% reduction in energy consumption due to these
measures:
4. Additional energy savings = 100,000 kWh * 10% = 10,000 kWh per month

23. Case Study (Cont.)
 Total Monthly Energy Savings:
• Energy savings from efficiency upgrades: 46,670 kWh
• Additional savings from smart controls, VFDs, and occupancy sensors: 10,000 kWh
• Total monthly energy savings: 46,670 kWh + 10,000 kWh = 56,670 kWh
 Cost Savings:
• Cost per kWh: $0.12
• Total cost savings per month = Total energy savings * Cost per kWh
• Total cost savings = 56,670 kWh * $0.12 = $6,800.40
 Conclusion: By implementing these energy conservation measures, the company can
potentially save $6,800.40 per month in electricity costs while significantly reducing its
environmental footprint by cutting down on energy consumption.

24. References:
https://beeindia.gov.in/

25. Thank you…..