Thermodynamic analysis of an ejector-assisted ammonia-water absorption-resorption cycle

Abstract

The absorption-resorption cycle can supply the cooling and heating effect at lower operating pressures than the more traditional vapour absorption cycle (vac). The proposed cycle has cost reduction potential in reducing heat exchangers size for the lower pressure values and higher performance than the conventional cycle. This study evaluates the performance of an ejector-assisted ammonia-water absorption-resorption cycle in which the solution expansion valve is replaced with an ejector. The ejector boosts the absorber pressure by recovering the expansion work from the high-pressure solution stream. The coefficient of performance (cop) of the proposed cycle is evaluated and compared with the conventional ammonia-water vapour absorption-resorption cycle (varc) without the ejector. A parametric analysis is performed to demonstrate the effect of different pressure ratios on the cop, mass fraction gradients, generator circulation ratio, heat inputs, and heat rejections. For a constant high pressure, the low cycle pressure is varied in the feasible region, and the cop of the proposed cycle is evaluated at different desorber, generator, and absorber operating temperatures. At 6 bar resorber operating pressure, the cop value of the proposed cycle is 5 % higher than the conventional varc. The results indicate that the cop value increases with increasing the cycle compression ratio, increases and attains a maximum value with the generator temperature, but decreases with the absorber temperature. © ecos 2021 - 34th international conference on efficency, cost, optimization, simulation and environmental impact of energy systems.