Recently, the ozonosphere depletion and greenhouse effect was caused by using the CFCs and HCFs refrigerant into a heat pump and it have become more and more serious. Therefore, usage of existing refrigerant has regulated through the International agreement. The absorption chiller-heater using just the natural refrigerants has very little effects on the environmental pollution.
In the absorption chiller-heater, the HTG(high-temperature generator) using exhaust gas is an important factor to achieve high system performance. To investigate performance of the HTG using exhaust gas in the absorption chiller-heater, Lab. scale HTG using exhaust gas was designed and setup. Since it is very difficult to uses and control the 500oC exhaust gas, the experiment was performed using 200oC air instead of 500oC exhaust gas by using the dimensionless scaling method. It is very important to investigate the performance change of high temperature regenerator using exhaust gas according to the inlet condition of the exhaust gas and absorbing solution.
In this study, to analysis the performance of the HTG using exhaust gas in the absorption chiller-heater with operating conditions, the inlet condition of solution liquid and exhaust gas was changed. The Wilson Plot method for the exhaust gas of HTG was used to develop heat transfer coefficient of a fluid.
As the results, the more steam would be separated from absorption liquid within the HTG with the increase of the inlet temperature at air side. The 1st-outlet port of high-temperature generator shows more steam generation compared to that of other position port because it is located at the inlet of hot air which can supply most heat. Besides, the heat transfer efficiency of the HTG increases due to higher heat capacity and Re number with an increase of air mass flow ratio. As the air mass flow ratio increases from 80% to 120%, the heat capacity of 1st-, 2nd-, and 3rd-outlet port increases by 39.2%, 37.9%, 35.9%, respectively. When the absorption liquid outlet temperature is increased, the temperature difference between air and absorption liquid decreased. Thus, heat exchange rate is gradually decreased. Since the entropy increase rate increase of absorption liquid at outlet side is bigger than that of absorption liquid at inlet side, the heat capacity of HTG is decreased. When the inlet temperature of absorption liquid for 1st-, 2nd-, and 3rd-outlet port, the heat capacity of the HTG is increased by 14.5%, 17%, 14.8%, respectively. With the increase of the mass flow rate of absorption liquid at each outlet, the capacity of the HTG increased. when the mass flow rate of absorption liquid varies from 80% to 120%, the heat capacity of HTG at 1st-, 2nd-, and 3rd-outlet port is increased by 7.4%, 6.5%, 8.19%, respectively.
Wilson Plot method for the exhaust gas of high temperature regenerator was used to develop inlet and outlet tube heat transfer coefficient of fluid. As a result, index of Pr and Re number is 0.4 and 0.679, respectively.