Two dimensional transient coupled analysis of a finned tube adsorbent bed for a thermal wave cycle

Abstract

Poor heat and mass transfer inside the adsorbent bed of adsorption cooling cycles can cause low system performance. A 2-D mathematical model of the heat and mass transfer inside a cylindrical adsorption bed for a thermal wave adsorption cycle is developed, with a heat transfer fluid flowing through an inner tube and the adsorbent in the annulus. A parametric study is carried out for determining factors that enhance the heat transfer and mass transfer inside the adsorbent bed. The effects of several design and operating parameters on the transient changes in temperature, pressure and adsorption capacity of the adsorbent bed of a thermal wave adsorption cooling cycle are investigated. The transient response of the bed is presented using 2-D contour plots. The velocity of the heat transfer fluid is the most important parameter for the thermal wave behavior. For 0.001 m/s heat transfer fluid velocity and 0.013 m adsorbent bed thickness, the thermal conductivity of the adsorbent material has a significant impact on heat transfer for thermal conductivities less than 1 W/(m K). For 0.001 m/s heat transfer fluid velocity and 5 W/(m K) adsorbent thermal conductivity, adsorbent bed thicknesses larger than the inner heat transfer fluid tube radius causes hysteresis in the temperature front progressing with the heat transfer fluid.