Experimental and numerical studies are carried out to find the heat transfer phenomena of heat exchangers of the exhaust waste gas in GHP (Gas engine driven Heat Pump) system.
An experimental apparatus consists of the plate-shell heat exchanger (HX2), gas heating unit and cooling water circulating unit. The HX2 has three plates with a corrugated trapezoid shape of a chevron angle of 30o. Hot gas flowing in one upward channel releases heat to cooling water in the other channel. The effects of exhaust gas flow rate, gas temperature and cooling water flow rate on the heat transfer coefficient are measured.
The result shows that the heat transfer coefficient of gas channel in HX2 is increased gradually with the increase of gas flow rate and gas temperature, and the pressure drop is also increased significantly. The proper design values of HX2 in GHP system, therefore, are suggested and the correlation equation for the heat transfer coefficient of gas channel is provided within the experimental region.
The numerical predictions of heat transfer characteristics for the plate-shell heat exchanger (HX2) and the shell-tube heat exchanger(HX1) are performed by FLUENT 5.0 software. Temperature distribution, flow pattern, and pressure drop in HX2 are obtained using approximately 150,000 mesh points. The results are compared with experimental data and applied in 20HP GHP system. And only the numerical analysis of the shell-tube heat exchanger (HX1) attached in gas engine cylinder manifold is carried out to see the trends of exhaust gas temperature difference, temperature distribution, and pressure drop by heat exchanger configuration.