Study On Analysis And Evaluation Of Heating And Air Conditioning Systems Based On Exergy And Thermoeconomics

New technology and system styles for heating and air conditioning emergecontinuously under building energy conservation. Correct analysis and evaluation ofthe systems are necessary for obtaining better performance. In this dissertation,heating and air conditioning systems were studied for their analysis and evaluationrelated to energy conservation and thermal comfort.The structural theory of thermoeconomics was applied to heating systems. Basedon detailed analysis of the system characteristics, the thermoeconomic model for thesystem was established from primary energy to room air. Cost analysis method forheating systems was established. Then exergy flow model for design condition wasestablished and exergy cost analysis was performed. System model was establishedbased on TRNSYS software, and the system was simulated and exergetic cost analysiswas performed for a whole heating season. The results showed that component withthe highest relative exergy destruction did not correspond to that with the highestincrease of unit exergetic cost. In order to decrease the unit exergetic cost of thesystem final product, the cost formation process and the performance of everycomponent should be analyzed. Components with large relative exergy destruction,low exergy efficiency or large increase of unit exergetic cost should all be considered.The results of the whole heating season showed that changes of load affect theperformance of every component and the increase of unit exergetic cost. Therefore,different load conditions should be considered for the analysis of heating systems.The evaluation method for terminal units of heating systems was studied to lay abasis for selection and design of terminal units. First, thermal comfort and energyconservation indexes and indoor thermal environment model were established. Thentaking low temperature radiant floor heating as an example, indoor thermalenvironment was simulated and evaluation indexes were computed, showing theapplication of the evaluation method proposed by this dissertation.Based on exergetic cost concept of thermoeconomics, evaluation method of airconditioning systems with different cooling sources was studied. Evaluation indexesfor energy conservation were established. The relationship between the index for thewhole system and those for every component was obtained, which could be used to analyze the impact of the index for every component on that of the whole system, andhelp with energy-saving design and retrofit.Main purpose of heating and air conditioning systems is to create comfortenvironment, hence, evaluation of such systems can not be done without evaluatingthe environment. Through on-site measurement and survey on the indoor thermalenvironment of a university classroom located in Shenyang city, Liaoning province,during class hour, the relationship among human thermal sensation, subjectiveevaluation and indoor thermal environment was studied.