Abstract
LiBr/Water absorption refrigeration cycle for automotive air-conditioning applications was simulated, studied and analyzed using ABSIM, a user oriented computer code designed for cycle simulation of absorption systems at steady state. This cycle would utilize the available combustion engine exhaust heat to supply energy to the generator. The design parameters and ambient conditions were chosen based on conditions under which automotive vehicles would operate in practice. Condenser and evaporator sizes and air-flow quantities were chosen to be similar to their counterparts in the current R-134a vapor compression cycle. The cycle would deliver up to 7 kW of refrigeration at maximum rated conditions. The COP is 0.72. It was concluded that generator temperature of 100°C is capable of producing the maximum capacity. Also, an exhaust temperature of 285 °C and flow rate of 0.046 kg/s are required to maintain a generator temperature at 100°C. Simulation results indicate that a satisfactory operation can be established in the high ambient temperature of 45°C with air-cooled condenser and absorber.
Simulation results for the proposed cycle include temperature, enthalpy, flow rate, concentration, pressure, and vapor fraction at each point in the cycle. Also, For each component of the cycle, UA, NTU, Effectiveness, CAT, LMTD, and heat duty are presented. Global parameters such as COP and capacity are also given. Plots were generated to understand the effect of generator temperature on other components and on the cycle performance.
