Exergy Analysis Of Ice Storage System With Cold Air Distribution

With the country’s rapid economic development, China is faced with more and more serious energy crisis, therefore to improve the energy efficiency of HVAC systems can make an important significance on sustainable development. Nowdays, there are two methods for energy systems. one is energy balance, which reflects that various of energy distinguish from each other only in quantity but quality; The other is exergy method, which can determine various types of energy in quantity and qu ality, considers the energetic nature and the energetic transaction, or the energy loss, the method can indicate the energy– saving direction for systems and equipments. This paper make exergy analysis for a ice storage system with cold air distribution, which includes the following three aspects:First of all, this paper deals with exergy balance model for ice storage system with cold air distribution, rotary wheel dehumidification air–conditionning syatem and liquid desiccant dehumidification.Based on the exergy balance model, its performance parameters, such as the cooling load, energy consumption and exergy efficiency, were calculated and compared with those of a rotary wheel dehumidification air– conditionning system and a liquid desiccant air– conditionning system under the same conditions according to experimental data of a practical project in Guang Zhou. The calculation results show that the exergy efficiency of ice storage system with cold air distribution is higher than that of the rotary wheel dehumidification system by 33.37% and higher than the liquid desiccant system by 19.56%, which conditionally means the proposed ice storage system with cold air distribution has much better performances.Secondly, this paper developed a exergy analysis model for a ice storage system with cold air distribution and its main surface air coolers. Based on this model, some analysis were done to study the influences made by heat and humidity ratio, fresh air ratio and temperature difference between supply air and indoor air on the exergy efficiency of the system and the exergy loss rate of its surface air coolers. Finally the weakest link and the optimal parameters were determined for system optimization. The simulation results shows that the exergy loss rate of the surface air cooler for secondary mixed air is positively proportional to the variation of heat and humidity ratio, while it is inverse for the other; The exergy loss rate of the surface air coolers for fresh air is positively proportional to the variation of fresh air ratio, while it is opposite for the other; The exergy loss rate of the surface air cooler for primary mixed air is positively proportional to the variation of temperature difference between supply air and indoor air, while it is inverse for the other.Furthermore, this paper developed a exergy analysis model for the refrigerating machine, Based on this model, some analysis were done to study the weakest link. The result considers that condenser is the main exergy loss equipment of the system. Finally, some suggestion is given for reducing exergy loss rate of the equipments and exergy efficiency of the system.