Experimental Investigation of Waste Heat Utilization of Vapour Compression Refrigeration System

International Journal for Research in Engineering Application & Management (IJREAM) ISSN : 2454-9150 Vol-04, Issue-06, Sep 2018 Experimental Investigation of Waste Heat Utilization of Vapour Compression Refrigeration System

1Abadh Bihari Mandal, PG Scholar, Department of ME, BIT Sindri, Dhanbad, India. 2Pankaj Kumar, Assistant Professor, Department of ME, BIT Sindri, Dhanbad, India. [email protected], [email protected]

Abstract- Increasing demand of energy and global warming is the current issue before us. Substantial increase of energy demand compelled us to think on waste heat utilization perspective. To mitigate the energy crisis and to save our environment recovery of waste heat is utmost necessary. Our main objective to present this paper is to show the percentage of waste heat utilization possible from condenser of a household refrigerator. The condenser of refrigerator acts as a heat pump and discharge heat inside room hence increases the room temperature. This discarded waste heat can be reutilized for number of domestic purposes such as heating water, maintaining food hot, cloths and grain drying. Experimentally we have shown that with waste heat recovery the overall COP of the system increases. By installing the waste heat recovery unit with domestic refrigerator it has become a multipurpose refrigerator fulfills both cooling and heating requirements. Keywords — COP, Domestic Refrigerator, Energy Saving, R-134a Refrigerant, VCR System, Waste Heat Recovery

I. INTRODUCTION temperature below the ambient temperature of the room. In most cases, household refrigerator uses air- cooled Energy demand and to mitigate the demand is the prime condenser. R134a refrigerant is now widely used in most challenge before our civilized society. All types of usable of the domestic refrigerators and automobile air- energy are comes from conversion of other unusable energy conditioners and are using POE oil as the conventional of the nature. Transfer of energy always takes place from lubricant. Generally, heat from the condenser side is higher temperature to lower temperature. Hence all heat dissipated to room air. If this heat is not utilized, it simply transfer processes involve systems at temperature gradient becomes waste heat. Refrigerator has become an essential are brought into contact. Therefore, they obey the first as commodity rather than need. Very few of us are aware well as the second law of thermodynamics. Heat transfer is about the fact that lot of heat is wasted to ambient by the a fundamental and very important area that deals with condenser of refrigerator. If this energy can be utilized energy and has long been an essential part of mechanical effectively then it will be an added advantage of engineering curricula all over the globe. Heat transfer commodity our project aims towards the same goal. processes are involved in a large number of engineering Refrigeration in simple language is absorption of heat applications such as waste heat recovery systems. It is from the place at a low temperature and dissipation of important for mechanical engineers to understand the heat to the place at a high temperature. principles of thermodynamics and heat transfer and be able to use right equation that govern the amount of energy The objective of this experimental investigation is to being transferred. By retro fitting a waste heat recovery design, construct and evaluate dual refrigeration system by system this waste heat can be recovered and can be utilized manufacturing an experimental apparatus of heat recovery for water and air heating purpose. The hot water and dry air system from the condenser and evaporator. Although studies thereby produced can be used for several household have been done before on dual refrigeration systems, more purposes. The hot water can also be stored in a tank for research could be done to further enhance the results later use. The modified system results in energy saving obtained by experimenting using different sets of working due to non-usage of electricity for heating water and air pair’s material and testing them in different conditions thus cost saving by combining both utilities (refrigeration and shape and sizes. For example, in experimentation and heating) in one system. with waste heat recovery system (WHRS) in refrigeration unit, Kaushik, Panwar, and Reddy in 2012 have found that A refrigerator is a common household appliance that 40% of condenser heat can be recovered through the consists of a thermally insulated compartment and which Canopus heat exchanger for typical set of operating when works, transfers heat from the inside of the conditions in a dual refrigeration system [3]. To generate compartment to its external environment so that the inside ice, the evaporator temperature must be< 0 . The above of the thermally insulated compartment is cooled to a system could generate a COP of about 1.2 to 1.4 and in

277 | IJREAMV04I0642059 DOI : 10.18231/2454-9150.2018.0729 © 2018, IJREAM All Rights Reserved. International Journal for Research in Engineering Application & Management (IJREAM) ISSN : 2454-9150 Vol-04, Issue-06, Sep 2018 this experimental setup the aim of maintaining the COP and then the extension of evaporator tube goes to the cold more than the above results. The main aim is to increase water chamber for producing drinkable cold water. Exit of the COP of system by utilizing energy. When the the cold water chamber is attached with the compressor condenser heat is utilized, COP of system will boost up. inlet of the refrigerator. After compression the superheated refrigerant inters the hot air chamber again. This experimental setup is made for multipurpose use by utilizing the waste heat of the condenser of the domestic refrigerator. It is a feasible setup which will provide the four effects to serve four purposes of domestic use such as cold storage, cold water, hot oven and hot water.

Figure 01: Flow diagram of refrigeration cycle

Figure 02: p-h diagram of refrigeration cycle

There is a need for hot dish and cold water simultaneously during office hours. To fulfill this requirement it would be Figure 03: Experimental setup of Waste Heat Recovery unit of VCRS better to achieve this is a single setup by utilizing the waste heat. A combined setup purposing a refrigerator and a microwave oven serves the need. As microwave oven and refrigerator separately consumes more electricity and left impact on surrounding. We need to find what temperature can be generating in the condenser and evaporator so that which foods can be warmed or cooled in the system. This experiment proves to utilize a combined system rather than a single system, where cooling and heating could be Figure 04: Block diagram of experimental setup produced continuously in places far away from conventional grid. Most rural and urban area may benefit III. DETAILS OF THE EXPERIMENTAL SETUP from this system in years to come. WITH PROCEDURE

II. FABRICATION OF EXPERIMENTAL SETUP A. Hot Air chamber The experimental setup is used to recover the waste heat from the condenser of the refrigerator. The setup consists of an insulated hot air chamber works as a microwave oven, the hot water chamber for water heating, a cold water chamber and the refrigerator cabin for cold storage. The superheat after compression is trapped in the hot insulated chamber for food heating. A portion of Condenser coil is mounted inside the hot chamber. The extension of the condenser coil is then mounted inside the hot water chamber. After passing the hot water chamber condenser coil is attached with the capillary tube for throttling. After throttling the refrigerant passes through the evaporator Figure 05: Hot Air chamber cabin chamber of the refrigerator taking the heat of storage media

278 | IJREAMV04I0642059 DOI : 10.18231/2454-9150.2018.0729 © 2018, IJREAM All Rights Reserved. International Journal for Research in Engineering Application & Management (IJREAM) ISSN : 2454-9150 Vol-04, Issue-06, Sep 2018

Hot air chamber is mounted at the top front side of the water chamber. The cold water chamber is an aluminum pot refrigerator body. A fan is also mounted at the back side of of one liter capacity. Since the extension of the evaporator the chamber for the force circulation. This hot air chamber coil surrounds the aluminum pot the water in the pot getting is an old microwave oven body with proper ventilation for cool. After the desired cold temperature attains by the water escaping of moisture. To fulfill the requirement of desired it can be drains out with water tab as shown in the figure. temperature attainment the door plays an important role For refilling, the fresh water is poured from the top opening while in closed condition and gives an elegant look. Due to of the outer box cover. Main objective for installation of small size of the compartment for this low capacity cold water chamber is to provide cold drinking water just to refrigerator it is limited for keeping food in hot condition eliminate drinking water bottle to put inside the refrigerator. only but for large capacity refrigerator it may serve for This setup will serve as a multipurpose refrigerator which grains and cloths drying. Concept behind this experimental will provide cold water, hot water and hot air chamber setup is to assemble this heating device with the refrigerator simultaneously by utilizing the waste heat of the which runs on waste heat of this refrigerator. This chamber refrigerator itself. is mounted in such a way that the overall height of this setup should not exceed a desired limit that can prevent it for easy utilization by an average height person. A switch is also provided for on/off of the fan according to the requirement of the hot air distribution inside the chamber. B. Hot water chamber

Figure 07: Cold water chamber D. Outer box of waste heat recovery unit

Figure 06: Hot water chamber Hot water chamber is mounted at the top back side of the refrigerator body which will be used for the water heating. The extension of the condenser coil after hot air chamber is again coiled under the hot water chamber. The hot water chamber is an aluminum pot of one liter capacity. The aluminum pot is placed over the heated circular coiled condenser tube is such a way that it cannot pollute the hot Figure 08: Outer box of waste heat recovery unit water. The hot water will be used for domestic purpose The outer box of GI sheet having following specifications hence the coil is not dipped inside the hot water. Since the listed below is mounted at the top of the refrigerator refrigerator is of low capacity the hot water temperature is chamber. It consists of the hot air chamber, hot water limited to attain a particular value. Since aluminum is a chamber and a cold water chamber with proper insulation. good conductor of heat and easily available in the market it There are two separation compartments that separate the has been used as a hot water chamber. The pot can maintain three chambers with each other with insulating material so the temperature of hot water for long time a proper that the exchange of heat cannot takes place with each other insulation is provided on its surrounding. When the hot of the compartments. water temperature attains a desired limit it can drain out for domestic purposes with the water tab connected to it. For Table 01: Specification of outer box of waste heat recovery unit refilling the freshwater a hole of diameter equal to the pot Material GI sheet diameter is cut on the top cover of the outer box. Length 24 inch C. Cold water chamber Cold water chamber is mounted at the top back side of the Width 20 inch refrigerator body besides hot water chamber. This chamber Height 10 inch will serve for cold drinking water purpose. The extension of the evaporator coil after the refrigeration surrounds the cold

279 | IJREAMV04I0642059 DOI : 10.18231/2454-9150.2018.0729 © 2018, IJREAM All Rights Reserved. International Journal for Research in Engineering Application & Management (IJREAM) ISSN : 2454-9150 Vol-04, Issue-06, Sep 2018

IV. RESULTS AND DISCUSSION  Figure 09 shows the variation of hot water temperature with time for both conditions i.e., when hot air In order to describe the experimental outcomes, graphs are chamber door is kept open and when hot air chamber plotted between different parameters obtained from number door is closed. As the condenser temperature increases of observations. the water at hot water chamber gets heat from Hot air chamber door open Hot air chamber door closed condenser and hence its temperature increases. After a span of one hour time hot water temperature reaches a

50 temperature of 40.7 for open door condition of hot ˚C) 40 air chamber and a temperature of 47.3 for closed 30 door condition of hot air chamber then becomes 20 saturated for both the conditions. It is cleared from

10 graph that when hot water temperature required is Hot water water Hot 0 more, hot air chamber door should be closed. temperature ( temperature 0 50 100 150 200  Figure 10 shows the variation of hot air chamber Time (min) temperature with time, when the door of hot air chamber is closed then more temperature can be Figure 09: Variation of hot water temperature with time obtained as compared to door open condition. Depending upon the requirement of inside temperature Hot air chamber door open

of hot air chamber, the door can be kept close or kept Hot air chamber door closed open. When high temperature is required in short time

˚C) 60 50 for food heating, hot air chamber door should be 40 closed. 30  Figure 11 shows the variation of evaporator box 20 10 temperature with time, when hot air chamber door is

0 kept open lower the temperature can be obtained but Hot air chamber air Hot temperature ( temperature 0 100 200 when hot air chamber door is closed the cooling Time (min) capacity of evaporator decreases. Since the heat of Figure 10: Variation of hot air chamber temperature with time condenser coil is trapped due to door closed condition

the cooling capacity decreases. Hence if more cooling Hot air chamber door open is required in less duration of time the door of hot air Hot air chamber door closed chamber should be kept open.  Figure 12 shows the variation of cold water 35 temperature with time for both open and closed door 30 condition of the hot air chamber. The lowest ˚C) 25 20 temperature of cold water is about 25 for open door 15 condition and about 27 for closed door condition of 10 hot air chamber. Since the thermostat temperature of 5 refrigerator is maintain at about 4 hence the cold 0

Evaporator box box Evaporator water temperature is not reached to very cold but can temperature ( temperature -5 0 50 100 150 200 be reached with variation of thermostat that regulates -10 the saturation temperature. Also when low temperature Time (min) Figure 11: Variation of Evaporator box temperature with time of cold water is required the hot air chamber door should be kept open.

Hot air chamber door open Comparison between door closed and open condition for Hot air chamber door closed hot air chamber has been easily noticed from the graph and

35 30 decision can be taken according to the requirement. Graph ˚C) 25 shows that after a time span the saturation condition have 20 reached for all the parameters. 15 10 V. CONCLUSION 5 Cold water water Cold 0  This experiment shows that the recovery of waste heat temperature ( temperature 0 50 100 150 200 from the condenser of a refrigerator is possible up to 45%. Time (min) Figure 12: Variation of cold water temperature with time

280 | IJREAMV04I0642059 DOI : 10.18231/2454-9150.2018.0729 © 2018, IJREAM All Rights Reserved. International Journal for Research in Engineering Application & Management (IJREAM) ISSN : 2454-9150 Vol-04, Issue-06, Sep 2018

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