Agrawal, A.K.Bisen, Pankaj2016-05-302016-05-302014http://krishikosh.egranth.ac.in/handle/1/66457The present investigation is aimed to evaluate the performance of solar water heated shell and tube heat exchanger, to develop milk pasteurization system using solar heated water and to assess the chemical and microbial qualities of pasteurized milk prepared using solar heated water. The shell and tube heat exchanger performance was evaluated considering solar water flow rates of 3, 5,and 7 l/min at 850C and cold water flow rates at 0.5, 1.0 1.5 l/min at 350C. Theparameters like rate of heat transfer from hot water (Qh) and to cold water (Qc), log mean temperature difference (LMTD), overall heat transfer coefficient on the basis of inner tube (Ui) on the basis of outer tube (Uo), effectiveness of heat exchanger (ε), number of transfer units on the basis of inner tube (NTUi) and outer tube (NTUo), tube side (hi) and shell side (h0) convective heat transfer coefficient and tube wall temperature (Tw) were calculated. The average values of Qh were from 3.79 to 7.76 kW at 3 to 7 l/min and it was 5.17 to 6.44 kW at 0.5 to 1.5 l/min respectively. Similarly the average values of Qc (from 2.26 to 2.51 kW at 3 to 7 l/min and 1.31 kW to 3.43 kW at 0.5 to 1.5 l/min), LMTD (from 16.30oC to 15.24oC at 3 to 7 l/min and 16.63 to 16.65oC at 0.5 to 1.5 l/min), Ui (from 5.21 to 6.18 kW/m2 oC at 3 to 7 l/min and 3.41 to 7.95 kW/m2 oC at 0.5 to 1.5 l/min), Uo (from 7.73 to 16.94 kW/m2 oC at 3 to 7 l/min and 11.95 to 13.02 kW/m2 oC at 0.5 to 1.5 l/min), ε (from 0.68 to 0.75 at 3 to 7 l/min and 0.76 to 0.67 at 0.5 to 1.5 l/min), NTUi (from 2.01 to 2.41 at 3 to 7 lImin and 2.53 to 1.96 at 0.5 to 1.5 l/min), NTUo(from 3.93 to 8.76 at 3 to 7 l/min and 10.18 to 3.69 at 0.5 to 1.5 lImin), hi (from 0.65 to 0.69 kW/m20C at 3 to 7 l/min and 0.39 to 0.94 kW/m20C at 0.5 to 1.5 lImin), h, (from 0.57 to 0.94 kW/m20C at 3 to 7 l/min and 0.76 to 0.74 at 0.5 to 1.5 lImin) and Tw(from 67.84 to 71.98oC at 3 to 7 l/min and 73.79 to 66.57oC) respectively. The values of heat exchanger effectiveness, number of transfer units, and tube wall temperature were found to be maximum in combination of flow rate of hot water at 7 l/min and flow rate of cold water at 0.5 lImin. The milk was pasteurized with this combination of flow rates. The pasteurized milk was evaluated for its chemical and microbial qualities and was compared with raw milk. The pasteurized milk had 0.15% acidity, 3.49% fat, 8.44% solid not fat and 11.93% total solids. In this way pasteurized milk was found more or less similar with raw milk. In microbiological quality evaluation, methylene blue reduction time was found 1.2 h for raw milk and 5.4 h for pasteurized milk. The total bacterial count were found 4.27 log 10 cfu/ml and coliform was found to be absent in 0.01 dilution for pasteurized milk. All the microbiological test findings found within the BIS standards specified for pasteurized milk. The cost of processing in conventional and solar water heated pasteurization was estimated to be Rs. 2.75 and Rs. 1.90 respectively. The finding of this investigation have shown that solar water heating system assisted shell and tube heat exchanger system can be used to produce pasteurized milk with acceptable quality.en-USpasteurization, milk productsThesis