Chili Wu

A field investigation of a solar-powered adsorption cooling system under Guangzhou's climate with various numbers of heat exchangers in the adsorbers

In the current study, a solar-powered double-bed adsorption cooling system has been built and tested in the Guangzhou climate. The effect of the pre-heating process on the cooling performance of the adsorption cooling system powered by solar energy has been experimentally investigated. A specific cooling power of 52.2 W/kg and a coefficient of performance of 0.20 were achieved under a 2-h pre-heating process with operating conditions of 26°C cooling water inlet temperature, 16°C chilled water inlet temperature, 8 L/min hot water and cooling water flow rate, 2 L/min chilled water flow rate and 600 s adsorption/desorption phase time. The average specific cooling power and coefficient of performance were improved by 26.1% and 33.3%, respectively, as compared to the case without conducting the pre-heating process. In addition, the influence of dead volume on the specific cooling power and coefficient of performance of the adsorption cooling system has also been investigated. Using various numbers of heat exchangers in the adsorber achieved different values of adsorber dead volume. The results show that a higher specific cooling power value is obtained with a smaller dead volume. Finally, the cooling performance of the adsorption cooling system was also studied under various operating conditions and a maximum specific cooling power and coefficient of performance are 180.4 W/kg and 0.29, respectively.

Influence of sinusoidal airflow and airflow distance on human thermal response to a personalized ventilation system

Since the concept of personalized ventilation was introduced in the late 1990s, many studies on thermal comfort have been conducted and a number of parameters identified. In this research, the influence of three parameters, the airflow speed, airflow fluctuating period and a parameter which has drawn less attention in previous studies – the airflow distance between the human subject and the nozzle of the personalized ventilation device on air movement perception, thermal sensation and thermal comfort – are studied. The combinations of fluctuating period and airflow amplitude were selected based on the Power Spectrum Density method. Then 25 human subjects participated in the thermal comfort experiment, each of them underwent 54 tests of different experimental conditions and expressed their thermal feelings by completing the survey questionnaire. Our findings showed that a longer airflow distance could lead to cooler thermal sensation, but not cause any difference in thermal comfort. Changing the fluctuating period of the sinusoidal airflow from 10 s to 60 s did not cause an influence on thermal sensation, but a shorter fluctuating period could result in a higher air movement perception. When dealing with thermal comfort issues, a joint effect with airflow speed and fluctuating period occurs and this should also be considered.