Theoretical Analysis of Heat Recovery Performance Air to Water of a Heat Pipe Heat Exchanger (HPHE)

Abstract

The purpose of this report is to analyze the heat recovery of the Heat Pipe Heat Exchanger (HPHE) by using ethanol as the working fluid. Heat pipe heat exchanger consists of 90 tubes were placed in staggered arrangement and inside the heat pipes was contained a screen wick and a working fluid. These pipes have been divided into three zones, consisting of evaporation zone, adiabatic zone, condensation zone, in each of zone, has a length of 500 mm, 100 mm and 500 mm, respectively. The mathematical models of HPHE which were simulated in MATLAB have the hot air flowing to evaporation zone with temperature range of 423.15 to 498.15K, and the cold water flowing to the condensation zone with a constant temperature of 303.15K. The ratio of hot air heat capacity rates to water heat capacity rates (C*) are in the range of 0.50 to 1.50. The results showed that the C* is 1.50 and the hot air temperature of 498.15K to be provided the best temperature for an exit cold water flow. The heat transfer coefficient of the hot air flowing to evaporation zone is 99.66 W/m2.K as well as the heat flux of condensation zone is 23.226 W/m2. Furthermore, at C* = 0.50 and the hot air temperature inlet of 423.15K, showed the best effectiveness equal to 0.538. Therefore, the results of the HPHE simulation can be used to design for the boiler in distillery.