Performance enhancement of adsorption heat pump using stratified thermal storage: Simulation results

A simulation study is presented for a novel cycle concept for adsorption heat pumps that makes use of a stratified thermal storage for internal heat recovery between the adsorption and desorption phases of the cycle. This system concept leads to improvement in the COP of adsorption systems and enables new combinations of efficient heat transformation and heat storage.
The loading and unloading from the storage using a stratification pipe and fluid extraction pipe is modelled in 1-D MATLAB model. A detailed parameter study involving the auxillary heater and cooler flow rates, heights of fluid extraction for the heater and the cooler are performed. Simulation results of different models incorporating different adsorbent materials (zeolites) and different energy storage fluids (thermo-oil and water) are compared for the system COP. Moreover, a system concept utilising the adsorption system in combination with an additional heat storage for solar thermal applications is introduced. For low-temperature room heating, this system coupling enables a thermodynamically efficient storage at elevated temperature.