Golden Research Thoughts

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1 Vol 4 Issue 6 Dec 2014 ISSN No : ORIGINAL ARTICLE International Multidisciplinary Research Journal Golden Research Thoughts Chief Editor Dr.Tukaram Narayan Shinde Publisher Mrs.Laxmi Ashok Yakkaldevi Associate Editor Dr.Rajani Dalvi Honorary Mr.Ashok Yakkaldevi

2 Welcome to GRT RNI MAHMUL/2011/38595 ISSN No Golden Research Thoughts Journal is a multidisciplinary research journal, published monthly in English, Hindi & Marathi Language. All research papers submitted to the journal will be double - blind peer reviewed referred by members of the editorial board.readers will include investigator in universities, research institutes government and industry with research interest in the general subjects. Flávio de São Pedro Filho Federal University of Rondonia, Brazil Kamani Perera Regional Center For Strategic Studies, Sri Lanka Janaki Sinnasamy Librarian, University of Malaya Romona Mihaila Spiru Haret University, Romania Delia Serbescu Spiru Haret University, Bucharest, Romania Anurag Misra DBS College, Kanpur International Advisory Board Mohammad Hailat Dept. of Mathematical Sciences, University of South Carolina Aiken Abdullah Sabbagh Engineering Studies, Sydney Ecaterina Patrascu Spiru Haret University, Bucharest Loredana Bosca Spiru Haret University, Romania Fabricio Moraes de Almeida Federal University of Rondonia, Brazil George - Calin SERITAN Faculty of Philosophy and Socio-Political Sciences Al. I. Cuza University, Iasi Hasan Baktir English Language and Literature Department, Kayseri Ghayoor Abbas Chotana Dept of Chemistry, Lahore University of Management Sciences[PK] Anna Maria Constantinovici AL. I. Cuza University, Romania Ilie Pintea, Spiru Haret University, Romania Xiaohua Yang PhD, USA...More Titus PopPhD, Partium Christian University, Oradea,Romania Editorial Board Pratap Vyamktrao Naikwade Iresh Swami ASP College Devrukh,Ratnagiri,MS India Ex - VC. Solapur University, Solapur R. R. Patil Head Geology Department Solapur University,Solapur Rama Bhosale Prin. and Jt. Director Higher Education, Panvel Salve R. N. Department of Sociology, Shivaji University,Kolhapur N.S. Dhaygude Ex. Prin. Dayanand College, Solapur Narendra Kadu Jt. Director Higher Education, Pune K. M. Bhandarkar Praful Patel College of Education, Gondia Sonal Singh Vikram University, Ujjain Rajendra Shendge Director, B.C.U.D. Solapur University, Solapur R. R. Yalikar Director Managment Institute, Solapur Umesh Rajderkar Head Humanities & Social Science YCMOU,Nashik S. R. Pandya Head Education Dept. Mumbai University, Mumbai Govind P. Shinde Bharati Vidyapeeth School of Distance Education Center, Navi Mumbai Chakane Sanjay Dnyaneshwar Arts, Science & Commerce College, Indapur, Pune Awadhesh Kumar Shirotriya Secretary,Play India Play,Meerut(U.P.) G. P. Patankar Alka Darshan Shrivastava S. D. M. Degree College, Honavar, Karnataka Shaskiya Snatkottar Mahavidyalaya, Dhar Maj. S. Bakhtiar Choudhary Director,Hyderabad AP India. S.Parvathi Devi Ph.D.-University of Allahabad Sonal Singh, Vikram University, Ujjain Address:-Ashok Yakkaldevi 258/34, Raviwar Peth, Solapur Maharashtra, India Cell : , Ph No: ayisrj@yahoo.in Website: Rahul Shriram Sudke Devi Ahilya Vishwavidyalaya, Indore S.KANNAN Annamalai University,TN Satish Kumar Kalhotra Maulana Azad National Urdu University

3 Golden Research Thoughts ISSN Impact Factor : (UIF) Volume-4 Issue-6 Dec-2014 Available online at GRT EFFECT OF SPIRAL TUBE HEAT EXCHANGER ON COP OF DOMESTIC REFRIGERATOR BY USING DIFFERENT EXPANSION VALVES. 1 2 Anil S. Katarkar and M. Basavaraj 1 P. G. Scholar:Mechanical Engineering, Ballarpur Institute of Technology,Ballarpur, India. 2 Principal, Ballarpur Institute of Technology, Ballarpur, India. Abstract:-The energy performance of Refrigeration systems are usually evaluated based on the laws of thermodynamics. However, compared to energy analysis, exergy analysis shows better and accurate location of inefficiencies. Exergy analysis locates inefficient areas having greater potential for improvement. Exergy analysis helps to understand and quantify system irreversibility s, to measure to reduce these irreversibility s to minimum level, and to optimize Refrigeration systems.this paper describes the construction and testing of an integrated sub cooled system which has been designed to enhance the performance of a domestic refrigerator by using water cooled spiral tube heat exchanger with the different expansion valve. This heat exchanger operates in parallel with the air-cooled condenser tubing of the refrigerator so that either one or the other is active when the refrigerator is running. The refrigerator was housed in a controlled-environment chamber, and it was instrumented so that its performance could be monitored carefully. The system has been fabricated according to literature study which is different from the one which is not reported issues associated with commercial implementation of the concept; and results are motivate to work on such topic in deeply. Keywords:COP; refrigeration system; water cooled heat exchanger;expansion valves. INTRODUCTION It is very much essential to put more efforts for improving the efficiency of thermal systems because of increasing energy prices and increasing concern of global warming. One of the methods of increasing efficiency in refrigeration system by sub cooling the refrigerant.extensively investigation work on increment in COP of VapourCompression Refrigeration and VapourAbsorption system by the various techniques, some of them had carried test using different geometry in condenser. Result may encourage the COP increment by addition heat exchanger in VCR system along with condenser for sub cooling process which is cost effective technique. LITERATURE REVIEW The focus is placed on a need to develop effective, less costly and maintenance-free auxiliary integrated with main system to achieve COP increment by varying expansion valves. If this idea is implemented at system design level, then there would be considerable saving of energy. Following researchers contributed to the area of COP increment significantly. Clark et al. [1] carried out experimentation on 18 ft3domestic refrigerator. They used water cooled condenser and regular air cooled condenser in parallel. Following are the findings of this research: (i) rise in temperature of cooling water is 350C in 100 hours of continuing operation, (ii) 18% - 20% energy savings for hot water, and (iii) no deterioration of the refrigerant performance. Yilmaz [2] carried out experimentation on air condition unit. He used concentric tube type heat exchanger for heat recovery. He found that, when entering water temperature is less than ambient air temperature, efficiency of air conditioning unit is improved. 1 2 Anil S. Katarkar and M. Basavaraj, EFFECT OF SPIRAL TUBE HEAT EXCHANGER ON COP OF DOMESTIC REFRIGERATOR BY USING DIFFERENT EXPANSION VALVES., Online & Print 1

4 Stinson et al. [3] conducted research in dairy refrigeration by recovering the heat from condenser. They found out that by using the water cooled condenser COP of the system is enhanced by 10% to 18%. They also found that increase in condenser pressure reduces COP, and inclusion of heat recovery heat exchanger reduces head loss. Alex et al. [4] prepared an analytical model of a residential desuperheater. They found that the results of mathematical model and results of experimental setup vary within 12%. Rane et al. [5] developed sensible heat recovery unit and carried out experiments. Waste heat recovered is utilized for water heating. Their findings are: (i) chiller cooling capacity enhanced by 30% and COP by 20%, (ii) fuel saving reported 81liters HSD/day, annual savings of Rs. 10 Lakh/year, (iii) Reduction in CO2 Emissions 450 ton in 4 years, and (iv) simple payback of 3 to 6 months. Jie Ji et al.[7] The technology of using a heat pump for space conditioning and domestic hot water heating in residences has been developed for half a century. The earlier air-to-water heat pumps and water-heating heat pumps suffered from drawbacks like high costs, unreliable operation, and inflexible applications. They were not well positioned in the market to attract customers. This paper introduces a novel air-conditioning product that can achieve the multi-functions with improved energy performance. The basic design principles and the laboratory test results are presented. The results showed that by incorporating a water heater in the outdoor unit of a split-type air-conditioner so that space cooling and water heating can take place simultaneously, the energy performance can be raised considerably. S. C. Walawade[8] energy saving is one of the key matters from view point of fuel consumption and for the protection of global environment. So it is necessary that a significant and concrete effort should be made for conserving energy through waste heat recovery too. The main objective of this paper is to study Waste Heat recovery system for domestic refrigerator. An attempt has been made to utilize waste heat from condenser of refrigerator. This heat can be used for number of domestic and industrial purposes. In minimum constructional, maintenance and running cost, this system is much useful for domestic purpose. It is valuable alternative approach to improve overall efficiency and reuse the waste heat. The study has shown that such a system is technically feasible and economically viable. Y. A Patil& H.M. Dange[9] refrigerator has become an essential commodity rather than luxury item. The heat absorbed in refrigerated space and the compressor work added to refrigerant is too rejected to ambient through a condenser. Our aim is to recover waste heat from condenser unit of a household refrigerator to improve the performance of the system. The heat recovery from the household refrigerator is bythermo siphon. From the experimentation it was found that after recovering heat from the condenser of the conventional refrigerator its performance get improved than conventional refrigerator. The maximum temperature achieved in water tank with 100 liter of water is 45ºC at the full load condition. If the water tank contains 50 liter water then it gets heated to 45 ºC in just 5 to 6 hrs. After that performance of the system gets decreased. So it needs regular use of that hot water. Thakre S. H. [10] Waste heat recovery is the process of capturing waste heat (thermal) energy for beneficial purposes. Energy savings and efficiency improvements of energy systems are important tasks on the path towards a more sustainable future. Conventional power stations convert only about 33% of their input heat to electricity. The remaining 67% emerges from the turbines as low-grade waste heat with no significant local uses so it is usually rejected to the environment. The present work is based on these low conversion efficiencies, strongly suggesting to find productive usesfor this waste heat. It is found from the literature review that most of the research carried out is for recovery and utilization of partial superheat from condenser, which is further used for various applications. Studies aimed at COP increment by using different expansion valves are not reported in the available literature. In this context, it is essential to carry out the research for recovery of superheat and latent heat of condensation CYCLE ANALYSIS Fig. 1 illustrates a schematic outlines the respective cycles on a T-h diagram. The saturation temperature would rise in the condenser (ÄTc,sat, Fig. 1) which would subsequently increase the specific compression work (?w, Fig. 1). On the other hand, the refrigerant temperature at the condenser outlet would decrease (?Tc, out, Fig. 1), 2

5 increasing subsequently the refrigerant enthalpy difference through the evaporator (?q, Fig. 1). This logic can be expressed by Eq. (1) and suggests that COP may undergo a maximum, resulting from a trade-off between increasing specific refrigerating effect (by?q) and compression work (by?w). As illustrated in Fig. 1, strictly speaking, the subcooling (?Tc, sub) can be a result of both a decrease in refrigerant condenser exit and an increase in condensing temperature.the relative increase in refrigerating effect (?q/q) can be approximated by Eq. (3) which shows that the relative change in refrigerating effect due to the variation of the refrigerant outlet temperature to the condenser depends on the ratio of liquid specific heat to latent heat of vaporization and on the temperature lift, (Tc -Te)sat. It suggests that reducing the temperature of the refrigerant at the condenser exit would be more welcome for refrigerants with large liquid specific heat and smaller latent heat of vaporization and for operating conditions with high temperature lifts. A similar approach is taken for the relative increase in specific isentropic compression work (?w/w), given by Eq. (4). Fig.1.Schematic of cycles with and without sub cooling in a T-h diagram [10] EXPERIMENTAL SET-UP Figure-2 shows the experimental setup. It shows the spiral tube heat exchanger unit installed in parallel to air cooled condenser with conventional refrigeration or air-conditioning system. Spiral tube type heat exchanger is designed and installed in the cycle as shown in the figure. Three different expansion valve are attached in the path to find the optimum increment of COP of VCR system i.e. capillary tube, thermostatic expansion valve and hand operated expansion valve. Water tank is placed on upper side of the setup. Control panel consist of On/Off switch for evaporator, on/off switch for fan, Dimmerstat, energy meter, digital temperature indicator connected with 9 k- type thermocouple are attached and results are recorded and analyzed. 3

6 RESULT Fig.2.Experimental set up line diagram Experiments are carried out with heat exchanger and bypassing the heat exchanger. Mass flow rate of water circulation is changed and its effect on system performance is studied. It is found out that by using water cooled heat exchanger in the cycle, discharge pressure is reduced and work required to drive the compressor is reduced. For the analysis of cycle show outcomes of system with heat recovery unit respectively. Table-1 shows the refrigerating effect QE, condenser heat rejection QC, power consumed in kw, actual COP, and theoretical COP* water cooled heat exchanger. A C Fig.3. (A, B & C)Graph of Refrigerating effect vs work done for thermostatic valve, capillary tube & hand operated expansion valve. C A Fig. 4.AGraph of comparative study of Actual COP Vs Improved COP for different expansion valve. 4

7 In, Fig. 3A.Shows that the actual COP s for thermostatic valve with compared to sub cooled system; improved COP undergoes a maximum for refrigerants R134a. The maximum COP is a result of the trade-off between increasing enthalpy difference through evaporator and specific work (isentropic) of compression. The enthalpy at the evaporator inlet is reduced while the refrigerant exiting the spiral tube heat exchanger is sub cooled, thus enlarging the enthalpy difference across the evaporator for refrigerant. But compared to actual COP with improved COP it is found that the nature of graph is not a straight line; it seems that there is no constant improvement in the COP for thermostatic expansion, sometime it falls and again it increases. Actual COP up to 3.2 and improved COP is up to 4.4, means 27.29% of increment found in the COP for subcooling system in domestic refrigerator. COP improved may be more than the actual calculated because of following errors for all type of expansion valve which is used in domestic refrigerator for sub cooled system for this experimentation. 1. Heat out leak 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. In, Fig. 3B.Shows that the actual COP for capillary tube with compared to sub cooled system; improved COP undergoes a maximum for refrigerants R134a. The maximum COP is a result of increasing enthalpy difference through evaporator and specific work of compression. The enthalpy at the evaporator inlet is reduced while the refrigerant exiting the spiral tube heat exchanger is sub cooled, thus enlarging the enthalpy difference across the evaporator for refrigerant R134a. Actual COP with improved COP it is found that the nature of graph is not a straight line; it seems that there is no constant improvement in the COP for capillary tube, sometime it falls and again it increases. This observation is found for both the COP s in capillary tube. Actual COP up to 9.95 and improved COP is up to 20.12, means 50.54% of increment found in the COP for subcooling system in domestic refrigerator. In, Fig. 3C.Shows that the actual COP for Hand operated valve with compared to sub cooled system; improved COP undergoes a maximum for refrigerants R134a. The maximum COP is a result of increasing enthalpy difference through evaporator and specific work of compression. The enthalpy at the evaporator inlet is reduced while the refrigerant exiting the spiral tube heat exchanger is sub cooled, thus enlarging the enthalpy difference across the evaporator for refrigerant R134a. Actual COP with improved COP it is found that the nature of graph is not a straight line; it seems that there is no constant improvement in the COP for Hand operated valve, sometime it falls and again it increases. This observation is found for both the COP s in capillary tube. Actual COP up to 3.94 and improved COP is up to 8.33, means 52.75% of increment found in the COP for subcooling system in domestic refrigerator. As compared to other two expansion valve thermostatic valve shows higher actual COP and larger COP improvement due to heat recovery and sub cooling system in domestic refrigerator. The specific isentropic work of compression, however, first decreases at lower values of subcooling due to a reduction of the pressure ratio and an increase in the compressor inlet pressure even though the condensing pressure increases. In fig. 4A. This means that within lower values of subcooling the effect of the suction pressure increase on the pressure ratio is dominant over that of the condensing pressure increase. At higher values of subcooling, however, as the condensing pressure rises sharply its effect becomes dominant over that of the compressor inlet pressure decrease, thus elevating the pressure ratio and consequently the isentropic specific work of compression. Since the capacity was vary from kw kept nearly constant for each subcooling and the enthalpy difference across the evaporator increases with subcooling, the refrigerant mass flow rate is significantly reduced. As a consequence, refrigerant-side pressure drops across the system are reduced dramatically, as shown in observation table for suction line, evaporator and condenser. In the spiral tube heat exchanger, the growth of the sub cooled region also contributes to the decrease in pressure drop, as previously discussed. In the evaporator, an additional contribution to the pressure drop reduction is given by lower inlet qualities to the spiral coil. It confirms that the performance of the spiral tube heat exchanger for hand operated valve in terms of saturation temperature is dramatically worsened with the increase in subcooling because the sub cooled region introduces an area with lower temperature difference. The evaporator performance in terms of exit saturation temperature, however, does not seem to be affected, even though the refrigerant side pressure drop decreased significantly. 5

8 CONCLUSION Table. 1.1Result with water cooled spiral tube heat exchanger An experimental study about the effect of spiral tube heat exchanger subcooling on the performance of domestic refrigerator vapour compression systems has been presented probably for the first time in the open literature, to the best of the authors knowledge. This study showed that, as spiral tube heat exchanger subcooling increases, the COP undergoes a maximum as a result of a trade-off between increasing refrigerating effect, due to the reduction of the condenser exit temperature, and increasing specific compression work, due to the increase in the condensing pressure. The increase in condensing pressure was associated with the reduction of the air-refrigerant temperature difference and the refrigerant-side heat transfer coefficient once the two-phase region in the spiral tube heat exchanger is shrunken to accommodate the sub cooled liquid region. The results also showed that the thermodynamic properties associated with the relative increase in refrigerating effect, i.e. liquid specific heat and latent heat of vaporization, are dominant to determine the maximum COP improvement with spiral tube heat exchanger subcooling. Refrigerant with large latent heat of vaporization, such as R134a, tend to benefit the least from spiral tube heat exchanger subcooling for different expansion valve. In this review, many alternative vapour compression cycles applied to domestic refrigerator have been identified and presented. These vary from simple to complex cycles as well as from single-stage to multi-stage cycles, all emphasising any improved performance achieved. In general, the domestic refrigerator with sub cooled system all offer several benefits to vapour compression refrigerator such as reduced losses, increased performance, decreased energy consumption etc. when compared to the conventional basic vapour compression refrigerator without sub cooled at the same capacity. Along with improved performance, the complexity of the domestic refrigerator and the cost of systems increase due to the increased number of stages and the addition of new components. Currently, the economized cycle using a vapour injected compressor seems to be the most efficient for refrigerator for buildings both in its performance and compactness due to the operation of a single-stage cycle to a two-stage cycle. The application of refrigerator with sub cooled also has high potential. REFERENCES TIME QE Qc QS kw COP COP* Robert A. Clark, Richard N. Smith, and Michael K. Jensen [1996], An experimental study of waste heat Recovery From a residential refrigerator, , IEEE. 2.Dr.EminYilmaz [2007], Air conditioning waste heat to domestic hot water a study design report, Proceedings of IMECE, ASME International Mechanical Engineering Congress and Exposition, November 10-15, Seattle, Washington, USA. 3.G. E. Stinson, C. J. Stuman, D. J. Warburton [1987], A dairy refrigeration heat recovery unit and its effects on refrigeration operation, J. agric. Engng Res., 36, Alex H. W. Lee and J. W. Jones [1997], Analytical Model of a Residential De-superheater, Applied Energy vol. 57, No. 4, pp Milind V. Rane, Madhukar S. Tandale [2003], Benefits of superheat recovery on chillers case study for a hotel installation, International Congress of Refrigeration, Washington, D.C. 6.J & Dr. J. Hirunlabh [2001], International Journal of Ambient Energy, Volume 22, Issue 1. 7.Jie Ji, Tin-tai Chow, Gang Pei, Jun Dong, Wei He [2003], Domestic air-conditioner and integrated water heaterfor subtropical climate, Applied Thermal Engineering Vol. 23, p. no S. C. Walawade, B. R. Barve, P. R. Kulkarni [2012], Design and Development of Waste Heat Recovery System for Domestic Refrigerator IOSR Journal of Mechanical and Civil Engineering, PP: Y. A. Patil1, H. M. Dange [2013], Improving the Performance of Household Refrigerator by Recovering Heat from the Condenser, International Journal of Science and Research, Volume 2 Issue 6, June. 6

9 10.S.V. Diwan, Sagar H. Thakre, T. Chethan Kumar [2011], waste heat recovery-technology andopportunities in fuel oil area of athermal power plant, Dissertationreport of M.Tech in Thermal Engineering, VeermataJijabai Technological Institute, Mumbai. Anil S. Katarkar P. G. Scholar:Mechanical Engineering, Ballarpur Institute of Technology,Ballarpur, India. 7

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