1. WASTE HEAT RECOVERY SYSTEM
FROM DOMESTIC REFRIGERATOR
U.I.E.T C.S.J.M UNIVERSITY
Er. Arpit Srivastava
Dept. of Mechanical Engineering
UIET CSJM University
• In domestic refrigerator a
part of heat gets wasted out
• Wasted heat can be utilized
• system is technically
feasible and economically
5. DIFFERENT HEAT RECOVERY SYSTEM
• HRSG in gas power plant or turbine
• HVAC in steam power plant
• WHRS in refrigeration plant
6. SYSTEM DESCRIPTION
• Tested a WHRS and experimented to recover
condensation heat from domestic refrigerator
of 165 liter.
• By suitably retrofitting the WHRS in the unit ,
considerable waste heat is recovered.
• This heat is utilized for different purposes
8. HEAT EXCHANGER
A heat exchanger is a device used to transfer heat between
one or more fluids. The fluids may be separated by a solid
wall to prevent mixing or they may be in direct contact.
They are widely used in space heating, refrigeration, air
conditioning, power stations, chemical plants,
petrochemical plants, petroleum refineries, natural-gas
processing, and sewage treatment.
10. WHY COUNTER FLOW IN WHRS?
The counter-flow heat exchanger has three significant advantages over the
parallel flow design:-
The more uniform temperature difference between the two fluids
minimizes the thermal stresses throughout the exchanger.
The outlet temperature of the cold fluid can approach the highest
temperature of the hot fluid.
The more uniform temperature difference produces a more uniform rate of
heat transfer throughout the heat exchanger.
12. Putting all known values , we get;
Now calculating the value of r2 by hit and trial method:-
r2 LHS RHS
2.8 3 7.22
3 3 4.775
3.2 3 3.65
3.3 3 3.33
3.4 3 3.033
13. So r2=3.4mm
For Refrigerator of 165 liters capacity, given data from Kirloskar
Ltd manual follows- 
Refrigerator cooling capacity (amount of refrigeration produced
or heat extracted in refrigerator) =76 kcal/hr
= 88.392 W
Power required running the compressor (work done on
1/8 HP = 1/8×746 =93.25 W
Qcondensor = QEVOPORATOR + W COMPRESSOR
14. Assume efficiency of heat exchanger is 70%
So heat absorb by heat exchanger =QA
So heat receave by pipe through condenser is 127.149 watt.
• The transient respond of the body can be determine
by relating its rate of change of internal energy with
convection exchange at the surface
• Initially transient condition
• Steady state later
• Heat transfer through convection
17. Energy Supply
• Oven use low grade energy to work
• It use the waste heat, which is release to
• The refrigerant circulates through tubes
("refrigerant lines") that travel throughout the
• This circulated refrigerant dissipate heat to the
air inside oven
18. CONCEPTS & DESIGN
• Since the temperature of air inside oven varies with time
𝑻 𝒕 − 𝑻 𝒐
𝑻𝒊 − 𝑻 𝒐
−𝒉𝑨 𝒔 𝒕
𝐐(𝐭) = 𝐡𝐀(𝐓 𝐨 − 𝐓𝐢)[𝐭 +
−𝒉𝑨 𝒔 𝒕
Q= 𝝆𝑽𝑪(𝑻 𝒕 − 𝑻𝒊)
𝑄 =844.2 joules
T = 300 seconds
L = 0.6 meters
19. FABRICATION AND ASSEMBLY
• Parts of domestic refrigerator are as follows-
Modified Air cooled Condenser
Plate type Evaporator
Parallel type heat exchanger
20. Fabrication of Insulated Cabin
5.2.1 Material Used: Galvanized Iron Sheet
5.2.2 Process used - Sheet metal forming.
21. Fabrication of Cabin
• Inner box and outer box of insulated cabin are made
up of Galvanized iron sheet. After defining
dimensions, sheet metal working is performed. The
cabin is painted by silver color.
• Insulation material- here thermo Cole is used for
insulation purpose and it is of 3.5cm thickness.
• After forming all parts of cabin
it is assembled in well manner
as shown in
• The main aim is to use waste heat for domestic
• Waste heat from condenser is utilised.
• All above analysis results in utilisation of waste
• COP of refrigerator is also increased.
23. • Actual COP of refrigerator
COPactual = 0.948
• Improved COP of refrigerator
• Improvement in COP
COP improved varies than the actual calculated because of following errors.
1. Heat outleak while opening or closing the door cannot be exactly evaluated.
2. Actual COP is different than the value taken because the refrigerator is old.
3. Air may leak in or out because of old gasket.
Suitable heat recovery system can be designed and developed
for every household refrigerator.
The experimentation has shown that such a system is practically
Technical analysis has shown that it is economically viable.
If this can be started from individual level then it can sum up
and enormous effect can be obtained. Thus with small addition
in cost if we recover and reuse the waste heat, then definitely we
can progress towards energy conservation and simultaneously
achieve our day today function.
In present situation where everybody in a home is moving out,
this combination of refrigerator and food warmer is
definitely a boom to efficient
•  S.C.Kaushik, M.Singh., Feasibility and Design studies for heat recovery
from a refrigeration system with a Canopus heat exchanger, Heat Recovery
Systems & CHP, Vol.15(1995)665673.
•  P.Sathiamurthi, PSS.Srinivasan, Studies on waste heat recovery and
utilization. Globally competitive eco-friendly technologies engineering
National conference, (2005)39.
•  P.Sathiamurthi, PSS.Srinivasan “Design and Development of Waste
Heat Recovery System for air Conditioning Unit, European Journal of
Scientific Research,Vol.54 No.1 (2011), pp.102-110
•  C.P. Arora, Refrigeration and Air conditioning PHI Publications, 2010.
•  Er.R.K.Rajput, Heat and Mass Transfer, 4e McGraw Hill Publication
•  Design and Development of Waste Heat of domestic refrigerator
•  Frank P. Incropera and David P. Dewitt, Fundamentals of heat and Mass
Transfer 5e, Wiley India edition, 2008.