Yingjun Ruan

Optimal Sizing for Residential CHP System

Residential CHP systems have been introduced around Japan recently, and expected to diffuse more and more. During the process of boosting the adoption of residential CHP systems, both manufacturers and customers are interested to know the optimal capacity of power generator for the unit, and once the unit has been installed, what dispatch strategy to use in order to minimize a customer’s cost of meeting its electricity and heat demands.

Investigation on the Situation of Combined Heating and Power System in Japan

Abstract In Japan, during the last 20 years, combined heating and power (CHP) system has been developed rapidly. In order to grasp the present condition of introduction and the existing problems of CHP system, the questionnaire survey on CHP system had been carried out at Tokyo. According to the results of investigation, it can be summarized as follows: 1) CHP system had been used widely in various sectors. The generating electricity capacity ranged several ten to several thousands kilowatt. 2) The percentage of CHP total capacity to the electricity demand peak was low and the average value for all users investigated was only 25%. 3) Gas turbine and gas engine achieved 60%-80% overall energy utilization efficiency with 20%-34.5% generating electricity efficiency and 19.5%-50% exhaust heat utilization efficiency. 4) Education buildings had the maximum average generating electricity efficiency with 30.6%, followed by hospital buildings with 29.6%, amusement facilities with 29.5%, office buildings with 28% and compound buildings with 25%. Hospitals attained the maximum average exhaust heat utilization efficiency with 46.1%, followed by offices with 41.3% and compound buildings 39.8%. 5) Various users had different motivation of selecting CHP system. Both office and compound buildings selected economy as the most important reason introducing CHP system; while hospital and education users concerned more saving energy. Hospital and office users were satisfied with the CHP system introduced; while compound building users were not satisfied very much with the CHP system

Field Study and Sensitive Analysis of PV System by Multiple Regression Method

Abstract In this paper, the PV system in Kitakyushu Science and Research Park (KSRP) in Japan has been introduced. By analyzing the recorded data in 2002, the power generation result has been evaluated. On the basis of this, comprehensive module conversion efficiency for two different photovoltaic cells, single-crystal and multi-crystal, has been discussed. Furthermore, the factors influencing power generation amount and module conversion efficiency have been analyzed by using the single regression and the multiple regression method. And the environment contribution also has been evaluated. The results can be summarized as follows: 1) Although the PV system has been responsibility for little part of power consumption at KSRP, it has high reliability and stable running situation. 2) The average hourly module conversion efficiency is 10.6%, about 74.1% of comprehensive conversion efficiency with 14.3%. 3) Irradiance is the most important influence factor on power output of PV system and almost in direct proportion with power generation amount. The influence from air temperature is important than the one from wind velocity on power output, but the influence from them are both very small. 4) PV system has contributed to reduce environmental load greatly.

The Effects of Fuel Price and System Efficiency on Cost and Energy Savings in a Distributed Energy System

Abstract This paper presents a simple model of a distributed energy system, which was introduced in the Kitakyushu Science and Research Park, in order to evaluate the energy saving and operating characteristics of the distributed generation system. We analyzed the effects of fuel price and equipment efficiency on the operating time, running cost and energy saving. The increase of electricity price and decrease of gas price will enhance the attractiveness of the distributed energy resource. According to the load function of the system, energy-saving and environmental improvement will have a maximum value at its optimal operating time. Compared with heat recovery efficiency, power generation efficiency has more influence on energy saving and CO2 reduction when total efficiency of the system is assured.

Evaluation of the Introduction of a Combined Heat and Power System in a Commercial Building in Shanghai

Abstract This paper discusses the evaluation of a proposed combined heat and power (CHP) system for Jin Mao Tower (JM Tower), a commercial building in the centre of Shanghai. Because of the essential similarity in climate condition and latitude between Shanghai and Tokyo, electricity and heating consumption estimates are based on available Tokyo data. However this study does point out degree-days in order to guarantee the accuracy of energy consumption intensities of Shanghai. Two types of energy supply systems are considered: conventional and CHP. Environmental impact and economic efficiency are evaluated regarding the efficiency of both systems. Relative to the conventional system, CHP is capable of reducing the primary energy consumption by 23% and CO2 emission by 36%. The total annual running cost savings - the sum of energy, maintenance, and labour costs - are 11.8 million RMB, with a payback period of 3.8 years.

Examination of the Viability of Co-generation for a Small-scale Housing Development in Kitakyushu, Japan

Abstract A multidisciplinary team comprising researchers at Cranfield University at Kitakyushu, a local architectural and engineering practice and the Development Office for KSRP examined how urban form could enhance the opportunities for more sustainable development. Options for energy provision particularly was considered at the scale of the overall site development and for the individual dwellings, as apartments, terraced and detached housing. A holistic approach was taken for the development of a 1-hectare site in order to assess the potentials and opportunities for energy systems and environmental solutions at this scale. Subsequently a team from Cranfield University at Kitakyushu and the Environmental Engineering Faculty at Kitakyushu University investigated options for cogeneration on this development site in the form of Combined Cooling Heat and Power (CCHP). The options ranged from a centralised system based within the apartment building that served all the dwellings on the site to individual 1 kW electric cogeneration systems that served individual dwellings. A computer software model was used to examine the energy efficiencies of these options from hourly through to annual timescales, based upon typical electricity, heating, cooling and hot water consumption profiles for Japanese dwellings. In Japan a hot bathtub is filled each evening throughout the year and is used by the whole family. This constitutes a base load for hot water consumption that could be served through thermal storage. At present high output capacity gas boilers are used to provide the hot water for this purpose. Consequently, the computer models considered modes and scales of thermal storage as one of the key parameters for the examination of the relative viability of the options considered. The analysis was carried out using hourly weather data provided by a Test Reference Year weather data file for the local area.

Investigation and Evaluation on District Energy System at Kitakyushu Science and Research Park : Field Study on Running Situation during 2002(Environmental Engineering)

Abstract A district energy system in Kitakyushu Science and Research Park (KSRP) has been introduced. In this paper, the system′s running situation was analyzed by using the recorded data in 2002. Generating electricity, heat recovery efficiency and recovery heat utilization efficiency for gas engine and fuel cell were calculated. On the basis of the above study, energy saving and CO2 reduction were evaluated. The results can be summarized as follows: 1) The on-site generating electricity equipments provided 51.2% of the total electricity demand, including fuel cell with 34.5%, gas engine with 13.4% and PV system with 3.3%. In total heat energy demand, 70% of hot water load, 30.9% of cooling load and 14.3% of heating load were provided by recovering the heat energy from fuel cell and gas engine system. 2) Fuel cell was running 8572 hours with constant generating electricity efficiencies, about 30.8%. Gas engine only run 4281 hours with higher generating electricity efficiencies, about 24.5%. PV system achieved over 8% module conversion efficiencies in 83% of generating electricity time. 3) Fuel cell had lower heat recovery efficiency, but this heat energy recovered almost was utilized by the heat exchanger or absorption chiller. Gas engine had higher heat recovery efficiency, but only 70% of them were utilized by heat recovery equipments. 4) Compared with the conventional energy supply system, the district energy system achieved 56% primary energy utilization efficiency, 10.9% saving energy ratio and 1.32% CO2 reduction ratio.