Numerical analysis of heat pipe-assisted finned adsorber with FAM-Z02/water pair for vehicle air conditioning

Abstract

• Heat pipe-assisted finned adsorber for vehicle air conditioning. • Heat and mass transport between the heat pipe, fins and adsorbent particles. • Parametric study on SCP, COP and AAMR of FAM-Z02/water adsorber bed. • Optimal bed configuration considering number of fins and minimized weight. Adsorption cooling system (ACS) driven by engine waste heat is an attractive alternative to vehicle air conditioning (A/C) system. To find a compact and efficient solution for onboard application, a heat pipe-assisted finned adsorber unit tube (AUT) packed with FAM-Z02 adsorbent was studied numerically. Based on the integrated physical prototype, a three-dimensional numerical model was developed to investigate adsorption/desorption characteristics combined with experimentally validated heat pipe model and adsorption isotherm model. Moreover, specific cooling power (SCP), coefficient of performance (COP) and adsorber bed to adsorbent mass ratio (AAMR) were quantified to evaluate cooling capacity and system performance. It is found that, compared with adsorber without heat pipe, a 15.3% increment of SCP and 19.1% increment of COP can be achieved in the FAM-Z02/water based adsorber due to the contribution of heat pipe, and the AUT has an optimal SCP of 64.19 W/kg at the cycle time of 8510 s. The smaller adsorbent particle size leads to more refrigerant adsorbing/desorbing under the same cycle time, and FAM-Z02 with 0.1 mm diameter provides optimal SCP of 66.7 W/kg for ACS due to smaller particles possess less intra-particle mass transfer resistance. When the cool source temperature and heat source temperature are 300 K and 365 K respectively, higher SCP can be achieved due to the larger cyclic water uptake. Heat pipe-assisted finned adsorber offers a viable solution for coolant’s application in onboard ACS, and a 6-fin adsorber packed with 0.1 mm-diameter FAM-Z02 is considered optimal under lower adsorption temperature and higher desorption temperature.