Heat Transfer Characteristics Study on A Water–To–Water Heat Pipe Heat Exchanger using Effectiveness–NTU Method

P.RAVEENDIRAN; Dr.B.SIVARAMAN; Dr.K.SRITHAR

Volume : III, Issue : IX, September - 2014

Heat Transfer Characteristics Study on A Water–To–Water Heat Pipe Heat Exchanger using Effectiveness–NTU Method

P. Raveendiran, Dr. B. Sivaraman, Dr. K. Srithar

Abstract :

This paper presents the heat transfer characteristics of a water–to–water heat–pipe heat exchanger (W–W HPHE) experimentally. Methanol (CH3OH) is used as a working fluid. The analysis is based on the effectiveness (∈) –NTU (number of transfer units) approach to deduce its heat transfer characteristics. The experiment was carried out with various mass flow rate of water, inlet temperature of water in the evaporator section and heat input (Q) to the heat exchanger. The mass flow rate of water to the evaporator section varied from 30 lph to 60 lph, while in the condenser section it has been varied in the range of 10–60 lph. The mass flow rate of water in the condenser section has been altered in the ratio of 1:1, 1:1.5, 1:2, 1:2.5 and 1:3 as that of evaporator section. Several experiments were carried out under different operating conditions by varying the heat input to the heat exchanger from 1 kW to 4 kW. By varying the heat input to the heat exchanger, it is found that the inlet temperature of water to the evaporator section is varying in the range of 50–800C. In this study, the variation of overall effectiveness (∈) of W–W HPHE with heat capacity ratio (Ch/Cc) was presented and the effect of mass flow rate of water to the evaporator section and inlet temperature of water to the evaporator section were analyzed. The effect of mass flow rate of hot water to the evaporation section with respect to the overall heat transfer coefficient (U) also determined. It was shown that minimum effectiveness of W–W HPHE took place at Ch = Cc. Therefore equal value of mass flow rate of water in the evaporator and condenser section should be avoided. The optimum effectiveness is obtained when Ch = 2Cc for all heat inputs and mass flow rate of water to the evaporator section.