EXPERIMENTAL ANALYSIS FOR THE EFFECT OF COEFFICIENT
OF PERFORMANCE (COP) ON SOLAR REFRIGERATOR WITH
AXIAL D.C. FANS
Ratan Kumar, Parag Mishra and Ajay Singh
Mechanical Engineering Department, Radharaman Institute of Technology and Science Bhopal, Madhya Pradesh, India E-Mail: [email protected]
ABSTRACT
Domestic refrigerator is used in almost every household for preserving food, cooling water, freezing ice and many more. This research is done on a domestic refrigerator which is powered by solar panel. It is an attempt to analyse the effect of COP on a refrigerator. This experiment is conducted on a domestic refrigerator in which extra D.C. axial fans have been fitted in the back panel of refrigerator and these extra fitted fans cool the condenser faster than that of without fan. Therefore, the heat transfer from the condenser is more. In this experiment it is found that average coefficient of performance (COP) of domestic refrigerator with D.C. axial fans is higher than that of without D.C. axial fans by 0.038 in the studied range. This increment in COP is obtained due to the extra fans fitted in the back panel. It is also observed that the refrigeration effect (RE) of refrigerator with fan is about 7.02% higher than that of without fan.
Keywords: domestic refrigerator, D.C. axial fans, coefficient of performance, vapor compression refrigeration system.
1. INTRODUCTION
A refrigerator which is used in the household is generally called a domestic refrigerator and its compartment is insulated thermally. It transfers heat from inside compartment to the outside environment by the use heat pump and thus the refrigerator is cooled to the below room temperature. There are various researches going on in which performance of VCRS system can be increased. In this work solar energy is utilized to run the refrigerator. This solar energy is used to developed electricity by the use of a solar panel (a semiconductor material). This refrigeration system is powered by the solar panel electricity. M.Z. Sharif investigated in the field of VCRS in which he used nanorefrigerant and nanolubricant thus increased the heat transfer, thermal conductivity and COP [1]. Jai kishor Verma investigated for the economic sizing of the solar photovoltaic system for the domestic refrigerator [2]. For the domestic uses of PV cell, it is very important that it must be optimized. Due to optimized system it reduces the energy consumptions. Also replacement of the conventional condenser cause lower mass flow of the refrigerant which was experimented by F. Illán-Gómez [3]. The optimization of the refrigerator and its various parts along with energy saving were experimented by various researchers. Studies in the fields of refrigeration includes used of the fan on the spiral wire on tube condenser for optimizing the air flow field [4], along with air flow field the heat transfer performance was analysed for better performance by the use of multi-coil condenser with different orientation [13], energy saving analysis by thermal storage condenser and evaporator [5], improvement analysis on VCRS by evaporative condenser [6], improvement of the plant performance by the air cooled condenser and so on. Rahul Rawat also investigated for the optimization on the PV based system. In this investigation the system is optimized by the mathematical modelling equations and methodologies [7]. B.L.Gupta experimentally investigated the optimization of
the PV system for the domestic refrigerator. In this experiment the PV system is optimized by the optimization of the PV cell, battery capacity and insulation thickness for the domestic refrigerator [9]. Energy optimization is main concern among the researchers. Almost every field of the engineering it is the main criteria to cut down the energy consumption so that it can lead to the environment protection in some extent. Fatemeh Ghadiri experimented to find out the suitable refrigeration cycle components for the refrigerator to optimized energy consumption [10], Vahid Vakiloroayaa also studied in the field of energy optimization for the air cooled vapor compression air condition system [11]. Refrigerant is very important for the VCRS cycle because it is only substance which circulates inside the refrigerator. The performance of the refrigerator is directly connected to the refrigerant. So the refrigerant is also optimized for the better performance. A.S. Dalkilic analysed with different refrigerants on the VCRS cycle to compare its performance [14], also by replacing hydrocarbon refrigerant the efficiency analysis is investigated by Ching-Song Jwo [15].
1.1 VCRS cycle
to the evaporator. In the evaporator it gains heat and converted to the gaseous state. And this cycle repeats.
Figure-1. The schematic diagram of the VCRS cycle.
2. EXPERIMENTAL SET-UP
The experimental setup is a solar powered domestic refrigerator. The total components of this set-up are a domestic refrigerator, an inverter, a battery and a solar panel. In this set-up a domestic refrigerator is used which has the capacity of 165 litres which consume 92 watt of electricity. The components of the refrigerator are compressor, evaporator, condenser and expansion device. This refrigerator receives alternating current from inverter. The battery is charged by solar panel (poly crystalline solar cell). This battery supplies direct current to the inverter which converts direct current to the alternating current. In this set-up condenser has been redesigned and fabricated by four D.C. axial fans (75×75mm) placed back side of the refrigerator and inside of the condenser so that more heat transfer occur. Another change has been done in the higher and lower pressure side of the refrigerator by pressure gauges. One pressure gauge is added on higher pressure side and another is added on lower pressure side. For the temperature measurement thermocouple has been used. Here 5 J type thermocouples have been used. For showing the temperature at different places one temperature indicator has been used. One thermocouple is added over the tube of evaporator inlet. Second is added over the tube of evaporator outlet. Third is added over the tube of compressor outlet. Fourth is added over the tube of condenser outlet. Last one is placed inside the freezer.
Figure-2. Experimental set-up of refrigerator condenser with axial fans.
Figure-3. Pictorial view of experimental set-up.
2.1 Measuring devices
3. RESULTS
The results obtained from the experiments which are developed using the domestic refrigerator without fan and with fan.
Table-1. Average experimental data for the refrigerator without fan.
Time Freezer temp. (°C)
Refrigeration
effect (KJ/Kg) COP
11:30AM 3.57
12:00 PM 1.850 141.714 4.034
12:30 PM 0.142
1:00 PM -1.285 134.285 3.020
1:30 PM -2.142
2:00 PM -2.428 131.142 2.680
2:30 PM -2.857
3:00 PM -3.142 130.428 2.540
Table-2. Average experimental data for the refrigerator with fan.
Time Freezer temp. (°C)
Refrigeration
Effect (KJ/Kg) COP
11:30AM 1.285
12:00 PM -0.285 150.142 3.831
12:30 PM -1.714
1:00 PM -2.285 145.142 3.153
1:30 PM -3.142
2:00 PM -3.714 139.857 2.779
2:30 PM -4.000
3:00 PM -4.285 139.142 2.664
The result shows that the average COP for the refrigerator with fan is about 0.038 higher than that of refrigerator without fan which has shown in Figure-4. It is observed that COP for the first 60 minutes is lower for the refrigerator with fan but then it increases for the rest of the time. RE for the refrigerator with fan is 7.02% more than the refrigerator without fan which has shown in Figure-5.
Figure-4. Variation of COP of without fan and with fan with time (min).
Figure-5. Variation between refrigeration effect and time (min) of without fan and with fan.
Freezer temperature for the refrigerator with fan is lower than the refrigerator without fan which has shown in Figure-6. Condenser outlet temperature for the refrigerator with fan is lower than the refrigerator without fan which has shown in Figure-7. Compressor outlet temperature for the refrigerator with fan is lower than the refrigerator without fan which has shown in Figure-8.
2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2
60 120 180 240
C
OP
Time (minutes)
Refrigerator without fan Refrigerator with fan
125 130 135 140 145 150 155
60 120 180 240
Refri
g
e
ra
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(K
J/
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Time (minutes)
Refrigerator without fan
Figure-6. Variation between freezer temperature (°C) and time (min) of without fan and with fan.
Figure-7. Variation between condenser outlet temperature (°C) and time (min) of without fan and with fan.
Figure-8. Variation between compressor outlet temperature (°C) and time (min) of without
fan and with fan.
4. CONCLUSIONS
An experimental investigation studied on domestic refrigerator having D.C. axial fans for the analysis of coefficient of performance has been made. Various sets of experiments have been done for the analysis of domestic refrigerator with fan and without fan. The main conclusions from the observations and results can be summarized below:
In all the experimental tests result shows that average COP for the refrigerator with fan is about 0.038 higher than the refrigerator without fan. Only for the first hour COP of the refrigerator with fan is less but after that COP got an increasing trend. Therefore, the overall COP for the refrigerator with fan is higher than that of refrigerator without fan.
It is observed that RE for the refrigerator with fan is about 7.02% higher than the refrigerator without fan.
The experiment shows that the condenser temperature for the refrigerator with fan is lower than the refrigerator without fan.
The investigation also shows the difference in freezer cabin temperature is about 1-2 °C and the refrigerator freezer cabin temperature with fan is found to be lower than that of without fan.
REFERENCES
[1] M.Z. Sharif, W.H. Azmi, R. Mamat, A.I.M. Shaiful. 2018. Mechanism for improvement in refrigeration system performance by using nanorefrigerants and
-5 -4 -3 -2 -1 0 1 2 3 4
30 60 90 120 150 180 210 240
Free
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temp
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C)
Time (minutes)
Refrigerator without fan
Refrigerator with fan
30 32 34 36 38 40 42 44 46 48 50
30 60 90 120 150 180 210 240
C
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n
se
r o
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tl
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(°
C)
Time (minutes)
Refrigerator without fan
Refrigerator with fans
50 55 60 65 70 75
30 60 90 120 150 180 210 240
co
mpress
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temp
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°C)
Time (minutes)
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