Energy performance assessment of a novel zeolite-water direct contact adsorptive heat pump for waste heat recovery

•The low-grade industrial waste heat can be recovered using adsorption heat pumps.•The direct contact adsorption heat pumps guarantee simple configurations.•The water inlet downward flow configuration shows excellent thermal performances. The adsorption heat pumps are a promising technology suitable for the industrial waste heat recovery. In particular, the direct contact configuration can be used to generate high pressure steam for industrial applications limiting the design complexities. In this paper, a numerical simulation of the adsorption phase of an original configuration of a direct contact water/zeolite heat pump is presented and discussed. Two different models have been developed and compared using experimental data. Different sensitivity analyses were carried out with the aim of understanding the process of steam generation. The mass flow inlet results to be one of the most relevant parameters of the process and, consequently, an innovative process configuration is proposed. A descendent inlet water flow is implemented and compared with the classical ascendent process. The simulations on this configuration demonstrated that it is possible to obtain higher steam production and better process performances doubling the generated steam mass flow.