International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-9 Issue-2, December, 2019 3324 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: B3619129219/2019©BEIESP DOI: 10.35940/ijeat.B3619.129219 Abstract: Pasteurization coupled with refrigeration makes milk safe for human consumption and also extends the shelf-life of the milk. In a milk processing plant, hot water is used as heating medium and chilled water as cooling medium .In milk pasteurization heating and cooling process of milk was integrated by using plate heat exchangers known as regeneration section which saves 82.36% energy. Refrigeration plant for milk processing contributes approx. 30 % of total electricity load. This electricity load can be reduced by using vapor absorption refrigeration system (VARS) which requires heat input in the form of hot water. In the present study the VARS uses 1, 1, 1 tetrafluroethane (R134a) as refrigerant and n,n-dimethyl formamide (DMF) as absorbent. The COP of the system was obtained between 0.48 to 0.71 and refrigeration capacity varied from 0.69 kW to 2 kW. The absorption refrigeration system requires 1.4kW of hot water per kW of refrigeration capacity. Thus the integration of solar energy with absorption refrigeration plays important role in energy optimization and sustainable development in milk processing industry. Keywords: Pasteurization, Vapor absorption refrigeration system, Coefficient of performance, Dimethyl formamide, tetrafluroethane. I. INTRODUCTION Milk is an essential commodity but it is the most perishable and has only few hours of shelf life. To arrest bacterial growth and metabolism the temperature of the milk should be reduced to 2° C to 5° C within 4 hours hence, the time factor is the most important aspect in the milk processing. In dairy industry the first process integration was carried out due to plate heat exchangers for pasteurization process. In High Temperature-Short Time (HTST) pasteurization, heating and cooling of milk is carried out in plate heat exchanger (PHE). Due to PHE the regeneration section saves 82.36% energy in heating and cooling process of milk. Milk Cooling is done through a plate heat exchanger with cold water or brine being the cooling medium. This system has the advantages of being safe as the refrigerant is not directly used causing less damage in case of a leakage and the temperature can be easily controlled. The efficiency of plate heat exchanger is 20% higher than shell and tube heat exchanger [1]. Plate heat exchanger (PHE) acts as regenerator during pasteurization process and reduces Revised Manuscript Received on December 15, 2019. *Sanjay Mitkari, Research scholar at SVERI,s college of engineering Pandharpur, Maharashtra, India. Email: sgmitkari.nbnscoe@gmail.com sanjay.mitkari@raisoni.net Dr B P Ronge, SVERI,s college of engineering Pandharpur, Maharashtra, India. energy consumption in milk processing dairies. Before pasteurization the batch method is a widely used for fast cooling of milk. This ensures rapid milk cooling because in a very short time it can cool large amounts of milk and reduce the temperature of the milk below the critical value of 10 °C. Refrigeration plant for milk processing contributes approx. 30 % of total electricity load and the high price of electricity motivate to use absorption refrigeration in milk cooling.[2].After pasteurization milk is cooled by conventional vapor compression cycle which requires electrical energy. The increased energy cost and uncertainty in energy supply encouraged an investigation of heat operated refrigeration systems [3] .François Boudéhenna et al conducted experimental study on 5KW capacity absorption refrigeration systems and recommended use of plate heat exchangers to improve its performance [4,5]. To reduce this electrical load the VARS has been found to be useful as it uses hot water as heat input and chills the water/brine equal to or less than 0°C. VARS is a binary fluid i.e. refrigerant and absorbent and the selection of such binary fluid is very critical step in the success of VARS. In the present study 1, 1, 1 tetrafluroethane (R134a) is used as refrigerant and n, n-dimethylformamide (DMF) is used as absorbent which has high absorption capacity towards R134a and has very low partial pressure in the solution. Nezu et al have studied R134a as a refrigerant with various organic solvents as absorbent and showed that the R134a- DMF system is more advantageous than any other R134a-absorbent binary fluid pair [6].Giovani A Longo et al proposed a correlation to determine convective heat transfer coefficient for plate heat exchanger [7] Francisco Taboas studied plate heat exchangers as a generator and proved that the overall heat transfer coefficient depends on temperature of hot water. He also advised the use of waste heat or solar energy for such systems [8].Handong Wanga studied Diffusion Absorption Refrigeration driven by low-grade thermal energy such as solar energy and waste heat sources which can reduce the electricity [9]. The VARS has very low COP and these systems occupy large space therefore the development of more compact system is necessary to promote vapor absorption systems. In the present study commercially available compact brazed plate heat exchangers (BPHE) are used as the main components such as evaporator, condenser, absorber and generator. The system efficiency was experimentally investigated for solar hot water temperature in the range of 75°C to 90°C.The strong solution concentration ie rich in refrigerant was in the range of 51.56% to 73.77%.Integration of this system with milk processing is an important step towards utilizing clean source of energy and reduces electricity consumption. Application of Solar Absorption Refrigeration in Milk Pasteurization Sanjay Mitkari, B P Ronge