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Comparison of space cooling/heating load under non-uniform indoor environment with convective heat gain/loss from envelope
Building Simulation 2021, 14 (3): 565-578
Published: 30 September 2020
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The indoor parameters are generally non-uniform distributed. Consequently, it is important to study the space cooling/heating load oriented to local requirements. Though the influence of indoor set point, heat sources, and ambient temperature of convective thermal boundary on cooling/heating load has been investigated in the uniform environment in previous research, the influence of these factors, particularly the convective heat gain/loss through a building envelope, on cooling/heating load of non-uniform environment has not yet been investigated. Therefore, based on the explicit expression of indoor temperature under the convective boundary condition, the expression of space cooling/heating load with convective heat transfer from the building envelope is derived and compared through case studies. The results can be summarized as follows. (1) The convective heat transferred through the building envelope is significantly related to the airflow patterns: the heating load in the case with ceiling supply air, where the supply air has a smaller contribution to the local zone, is 24% higher than that in the case with bottom supply air. (2) The degree of influence from each thermal boundary to the local zone of space cooling cases is close to that of a uniform environment, while the influence of each factor, particularly that of supply air, is non-uniformly distributed in space heating. (3) It is possible to enhance the influence of supply air and heat source with a reasonable airflow pattern to reduce the space heating load. In general, the findings of this study can be used to guide the energy savings of rooms with non-uniform environments for space cooling/heating.

Research Article Issue
A fast distributed parameter model of ground heat exchanger based on response factor
Building Simulation 2017, 10 (2): 183-192
Published: 09 September 2016
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Downloads:15

Ground heat exchanger (GHE) is an important component of ground-coupled heat pump system. The soil temperature distribution and heat exchange capacity of GHE will largely determine the overall performance of the system. Consequently, it is very important for system design and its further performance improvement to seek a proper method of calculating the soil temperature field around GHE and the corresponding heat exchange rate. To break the limits of the existing calculating solutions and to improve the calculation accuracy and speed simultaneously, a fast distributed parameter model based on response factor (RF model) was proposed in this paper. The response factor refers to the contribution of a heat source to the excess temperature variation of a certain soil point. In a case study, the response factors and the temperature distribution of the soil heat container around one borehole were calculated using the RF model. Compared with results of numerical simulations, it can be known that the RF model equaled numerical solution in terms of accuracy, but enjoyed faster speed over numerical solution. In addition, the RF model was validated against the experiment data, with deviations less than 1.2%. In conclusion, the proposed RF model was a potential solution to predict the transient soil temperature distribution fast and accurately.

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