Study On Comprehensive Performance Evaluation For The Ground Source Heat Pump Air Conditioning System Combined With Chilled Water Storage

With the increasingly severe energy crisis nowadays, the economic and environment-friendly advantages of the ground source heat pump air conditioning system combined with chilled water storage(combined system) have become prominent gradually from the aspect of saving energy and emission reduction. With the extensive application of the combined system, it becomes a hot issue on how to evaluate the performance of this system scientifically in the field of HVAC.However, there are some problems on present assessment systems of the combined system, including the quality of assessment models are uneven, the evaluation factors are uncertain and the evaluation methods have the strong subjective, etc. In this paper, regarding comprehensive performance evaluation for the ground source heat pump air conditioning system combined with chilled water storage as the main clue, by using the building energy simulation software eQUEST and based on the summarizing current studies in the domestics and overseas, it gives a deep research on the evaluation factor selection, the determination of evaluation factor weight and the sensitivity of weight by using the methods of analytical network process(ANP), cluster analysis and the sensitivity analysis for weight. The main achievements are listed as follows:(1) Based on referring the domestic and foreign related literature and codes, the evaluation factors are determined considring the characteristics of the combined system.Including conventional energy replacement ratio, annual on-peak electricity energy transfer rate, annual off-peak electricity energy utilization rate, environment-friendly performance of the refrigerant, carbon emission reduction rate, the stable investment recovery period and net present value ratio. The software Super Decisions is used to obtain corresponding weights of these evaluation factors on the basis of the expert questionnaire.(2) Based on the whole year hourly dynamic load and the established mathematic model by the eQUEST, multivariable calculation for office and commercial building is carried out under variable system operation conditions. Then the results are analyzed using the cluster analysis method to determine the corresponding grade of different scores when the combined system is applied in both the two building types.(3) In this study, the method of sensitivity analysis for the weight of evaluation factors is introduced into the combined system performance evaluation system in order to research the influence of the change of evaluation factor weight on the result. According to the study, the combined system applied in office buildings is more sensitive to the stable investment recovery period and carbon emission reduction rate, while the system used in commercial buildings is more sensitive to the stable investment recovery period and net present value ratio.(4) By using the comprehensive evaluating method, a combined system used in an office building is evaluated. And evaluating results show the level of this combined system is first-class, but there are still some problems in this combined system, including long period of stable investment recovery, operation strategy remains to be optimized, etc. This application example illustrates the comprehensive evaluation method proposed in this paper not only can be used to evaluate the performance of combined system, but also can provide guidance for the optimization of system.