Yasunori Akashi

Energy and Cost Performance of a Cooling Plant System with Indirect Seawater Utilization for Air-Conditioning in a Commercial Building

This paper presents energy and cost performance of a cooling plant system with indirect seawater utilization for air-conditioning in a commercial building. The energy and cost performance is verified by direct measurement and a model-based simulation analysis. In the simulation, the indirect seawater utilization system is compared with a cooling tower system, an air source heat pump chiller system and a direct seawater utilization system. The electric energy consumption of the indirect seawater utilization system is almost the same as the other systems except the air source heat pump chiller system, because using lower seawater temperature can make the efficiency of the refrigerating machine higher, but this system also needs electric energy for cooling seawater/freshwater pumps. However, the indirect seawater utilization system can largely reduce demand charge compared with the cooling tower system, and cut down initial and maintenance costs compared with the direct seawater utilization system. Using these results, the effectiveness of the indirect seawater utilization system toward environmental conservation, energy and cost reduction is clarified in this paper.

Energy Performance of SOFC Cogeneration System for Residential Buildings in Chinese Cold Areas

Primary energy reduction and energy efficiency improvement are important targets to be achieved in every society and in residential buildings in particular. An energy-efficient and low-emissions solid oxide fuel cell (SOFC) cogeneration system is a promising electric and thermal energy generation technology for implementation in future residential buildings. This paper aims to analyze the energy performance in terms of primary energy demand and its reduction rate when SOFC cogeneration system is used in residential buildings. This study outlines SOFC cogeneration system and its simulation method, and then develops a standard family model for simulation under cold weather condition in China and selected Beijing city as an example, and finally compares them with traditional power and heat generation system based on gas and electricity. The results show that SOFC cogeneration system is an energy-efficient alternative power and thermal energy cogeneration technology for cold climatic cities such as Beijing, and can offer a large reduction rate (about 15.8% in winter) of primary energy demand in residential buildings. This study also finds that the significant reductions in primary energy demand of SOFC system result for the periods with air temperature decreasing.