Environment protection, industrialization, saving energy and modernization have become pertinent issues in the recent years. Approximately 20-40% of energy consumption in most modern cities can be traced back to buildings. Therefore, the increase in demand for heating and cooling systems in these buildings calls for proper designs.
Building cooling heating and power system can be used to meet varying load demands with a single primary energy. When compared to traditional counterparts, this system posts low pollution, and high economic benefit coupled with high energy efficiency. Nevertheless, the energy supply units within the building cooling heating and power system have low thermal performance under part load working conditions owing to non-synchronized as well as varying electrical and heating user demands. For this reason, a match between the energy supply and user demands is critical in the actualization of the power system.
Tsinghua University researchers led by Dr. Xin Wang in collaborations with Dr. Yin Zhang at Sichuan University developed a simple model of phase change material in thermal energy storage for building cooling heating and power system by taking into account user fluctuating load. This was in a bid to assess the effect of various thermal energy storage locations on the energy consumption of the entire system. They also investigated the effect of number of transfer units of the system. Their work is published in peer-reviewed journal, energy.
The authors settled for a model with a gas turbine, absorption chiller/heat pump, and thermal energy equipment composed of phase change material. In order to reduce the primary energy consumption, the authors performed the numerical simulation of the system with varying phase change material-thermal energy storage positions. How to determine the optimal energy storage position for saving primary energy consumption? Upstream or downstream?
For comparison, the authors collected results from an office unit and a typical hotel. Then, they began to investigate the effects of the performance of the phase change material-thermal energy storage system on the energy saving of the entire system. They did the analysis in summer and winter conditions.
For traditional models without the thermal energy storage equipment, the authors recorded an average gas turbine electricity generation efficiency of 30.9% and 31.5% for the hotel in summer and winter respectively. For the office block, they recorded generation efficiency of 32.4% and 29.3% for summer and winter respectively.
In a bid to enhance the part load performance of the system, the authors integrated a phase change material thermal energy storage device in the building cooling heating and power system, which was located either upstream or downstream. They confirmed from their results that phase change material thermal energy storage improved the energy saving of the developed system and reduced the installed capacity of the energy supply gadget. Also, they found that the energy saving ratio of the proposed system increased with an increase in number of transfer units of the thermal energy storage.
Only the downstream configuration would reduce the installed capacity of absorption chiller/heat pump. Downstream position becomes more preferable when users loads fluctuate greatly. The outcomes of this study provides for a stable means to design efficient phase change material thermal energy storage for integration in the building cooling heating and power systems.
Yin Zhang1,2, Xin Wang1, Yinping Zhang1, and Siwen Zhuo1. A simplified model to study the location impact of latent thermal energy storage in building cooling heating and power system. Energy, volume 114 (2016), pages 885-894.Show Affiliations
- Beijng Key Laboratory of Indoor Air Quality Evaluation and Control, Department of Building Science, Tsinghua University, Beijing, 100084, China
- College of Architecture and Environment, Sichuan University, Chengdu, 610065, China
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