Energy efficient operational processes of adsorptive heat storage device based on composite “silica gel – sodium sulphate”

Abstract

The present work is focused on the performance of the adsorptive heat storage device based on the composite adsorbent "silica gel-sodium sulphate" for the decentralized heating system. The following algorithm for calculating of the efficiency factor of adsorptive heat storage device is proposed calculation of the volume of air passed through the adsorbent layer, absolute humidity of air on the outlet of heat storage device, adsorption, heat of adsorption, operational inputs, such as heating the adsorbent up to the temperature of the beginning adsorption. The correlation of the adsorbent composition and the design characteristics of the heat storage unit has been revealed. The most efficient thermal accumulators are shown to be based on a composite, such as 80% sodium sulphate and 20% silica gel, which corresponded with the maximal values of the limit adsorption. Simulation of the performance of heat storage device based on the composites "silica gel-sodium sulphate" was carried out in the conditions of a typical heating system of residual premises. It has been shown that with steam moistening, the maximal values of the efficiency factor are observed when maximal value of adsorption achieved, the temperature of the humid airflow of 50-60 °C, the relative humidity of 55-60%, airflow speed of 0,4-0,6 m/s. For the first time the structure of inputs for the performance of an adsorptive heat energy storage device was analyzed for steam and ultrasonic moistering. For the first time expediency of the ultrasonic moistering was shown as a method to increase the efficiency of the adsorptive heat storage device. The optimal operational parameters of the adsorptive heat storage device under ultrasonic humidifying: the airflow speed is of 0,2-0,4 m/s and the relative humidity is 40-60%. These parameters allows to enhance the efficiency of the adsorptive heat storage device. Results of the present study can be used to develop energy efficient systems of decentralized heat supply, as well as ventilation and air conditioning.