Experimental Thermal Performance Study of a Baffled Heat-Pipe Heat Exchanger

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Author(s) P.Raveendiran | B.Sivaraman
Pages 706-715
Volume 3
Issue 7
Date July, 2013
Keywords Heat-Pipe, baffles, effectiveness (), number of transfer units (NTU), methonal.

Abstract

Experimental research has been carried out to investigate the thermal performance of a water-to-water baffled heat-pipe heat exchanger (B-HPHE). Methanol (CH3OH) is used as a working fluid. The analysis is based on the effectiveness () – NTU approach to deduce its heat transfer characteristics. Many factors influences the thermal performance of baffled heat-pipe heat exchangers such as temperature of water in the inlet of evaporator section, mass flow rate of water and heat input (q) to the heat exchanger. The mass flow rate of evaporator section varied from 30 lph to 60 lph, while 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. Many experiments were conducted under different operating conditions by varying the heat input to the electrical heater from 1kW to 4 kW, in order to determine and investigate their effect on the thermal performance of a baffled heat-pipe heat exchanger. 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 50-80oC. In this study, the variation of overall effectiveness () of B-HPHE with heat capacity ratio has presented and the effect of mass flow rate of water to the evaporator section, mass flow rate of water to the condenser section and inlet temperature of water to the evaporator section were anlaysed. The effect of inlet temperature of hot water to the evaporator section with respect to the overall heat transfer co-efficient (U) also determined. While attaching the baffles inside the shell, it was found that, for all operating conditions, the effectiveness of BHPHE has increased. The optimum effectiveness of a baffled heat pipe heat exchanger is obtained when mc = 50% of mh for all heat inputs and mass flow rate of water to the evaporator section.

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