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R & D in Sustainable Building Energy Systems and Retrofitting

Final Report Summary - R-D-SBES-R (R & D in Sustainable Building Energy Systems and Retrofitting)

The main aim of the R & D in Sustainable Building Energy Systems and Retrofitting (R-D-SBES-R) joint exchange programme is to develop and maintain long term partnerships between European and Chinese participant organisations by undertaking joint researches into the development of several zero (low) carbon cooling, heating and power generation technologies for buildings and promoting best practice and strategy for retrofitting existing buildings, by individual mobility of researchers between Europe and China. Its objectives are:
(1) to develop a novel dew point air cooler;
(2) to develop a solar driven ejector cooling system;
(3) to develop a solar driven desiccant cooling system;
(4) to develop a solar PV heat/power system using direct expansion evaporator/heat pipes;
(5) to develop a solar balcony hot water heating system;
(6) to develop a hybrid solar/biomass CHP system;
(7) to develop micro-channel heat exchangers for building air conditioning; and
(8) to develop best practice and strategy for building retrofitting.

The project was successfully managed and progressed very well. 5 project meeting were held annually in the project period. The secondments were undertaken successfully and European and Chinese participant organisations have developed long term relationships for collaborative research work in the future. Project meetings were held each year in the project period. Dissemination work included a project website, 4 workshops, 4 Conferences, 3 field trial demonstrations and publications including 87 Journal/Conference papers, 3 PhD/Master thesis and 8 books. 9 patents have been granted. 11 new research objectives have been established and funded by Royal Society, UK TSB/EPSRC and industries, 6 EU and China national awards have been granted for the work carried out during the project periods.

The development of the 8 technologies in this joint exchange programme have been completed, the details are as follows:

(1) Dew-point air cooler: A commercial dew point air cooler has been developed by the following steps: a) computer modelling and optimization of the dew point air-to-air heat and mass exchanger; b) design, construct and test a 2kW prototype dew point air cooler based on the results derived from computer modelling; and c) develop product catalogue. As a major part the dew point air cooler, a novel counter-flow heat exchanger constituted of corrugated sheets has been developed, which enhances the cooling capacity of the cooler for 20% and dew point/wet bulb effectiveness for 15%-23% compared to conventional dew point cooling heat exchanger.

(2) Solar driven ejector system: Computer simulation and lab testing has been carried out to optimise the components in the ejector system, including solar collector, PCM storage and ejector. The performance of the solar driven ejector system using different working fluids and for various operating conditions have been investigated. Experimental work has been carried out to investigate a 5kW steam ejector system that uses water as a working fluid and is environmentally friendly. It was concluded that for small scale cooling system, water can be used as the working fluid successfully.

(3) Solar driven desiccant system: The thermal and physical, and kinetics characteristics of different desiccant cooling materials have been investigated theoretically and experimentally. A 5kW solar-driven, two stage desiccant cooling prototype system with 5 kW cooling output has been developed. The test results showed that the desiccant cooling cycle can break the obstacle of limited temperate reduction encountered by conventional desiccant cooling cycle. The novel cycle can have a COP of 0.7~0.9 and is energy-saving, economical and environment-friendly.

(4) A building integrated solar PV heat/power system using direct expansion evaporator/heat pipes has been developed by theoretical and experimental investigation. The system consists of polyethylene heat exchanger loop underneath PV modules to form a PV/Thermal roof collector. The roof unit can convert part of the incoming solar radiation into power energy due to the photo galvanic effect of the silicon cells and remaining heat energy can be conveyed through the circulating water across the heat exchanger. The hot water can be used for heating & cooling, domestic hot water supply, food drying, building natural ventilation, etc.

(5) A solar balcony hot water heating system has been developed by theoretical and experimental investigations. A solar water heating system was constructed and installed at a balcony in a typical residential building in Guangdong (China). The year-round testing for balcony’s performance and operating characteristics were conducted. The thermal efficiency of the system under various solar/ambient conditions was obtained through measurement and subsequent calculation. The measurement data were compared with the modelling results, and the discrepancies were analysed.

(6) A novel hybrid solar/biomass CHP system has been developed by theoretical analysis/ computer modelling and prototype system lab testing. The experimental testing showed that a 25kW biomass boiler-driven micro-CHP system that has an ORC efficiency in the range of 2.20% - 2.85% can generate electricity of 344.6W and heat of 20.3kW corresponding to electricity generation efficiency of 1.17% and CHP efficiency up to 86.22%. For a 50kW biomass boiler-driven micro-CHP system that has an ORC efficiency of 3.48% - 3.89%, can generate electricity of 748.6W and heat of 43.7kW corresponding to electricity generation efficiency of 1.43% and CHP efficiency up to 81.06%.

(7) Micro-channel heat exchangers for building air conditioning has been experimentally investigated. Microchannel heat exchangers have advantages of improving heat transfer performance and decreasing system charge of the refrigerants. Investigation has been carried out on heat transfer and pressure drop characteristics of R22 substitute refrigerants with lower GWP value (such as R32, R152a, propane and R1234ze (E)) during condensation in microchannels. The experimental testing results showed show that R32, R152a, propane and R1234ze (E) are good substitutes for R22 based on the condensation heat transfer characteristics.

(8) Retrofitting strategies: Research has been carried out to develop retrofitting strategies utilizing other WP technologies, which includes research on comprehensive inspection and evaluation retrofitting technologies, research on retrofitting policy (i.e comparative related retrofitting policy and research on retrofitting policies and mechanism in China) and establishment on comprehensive retrofitting technical service platform. Guidelines on retrofitting have been developed.

The proposed project has developed the above several zero (low) carbon building energy systems and promoted implementation of best practice and strategy in China and EU building retrofitting. The economic and environmental analysis showed these energy systems are sustainable, low carbon and low cost. In line with increased global demand for energy in buildings, the research results will be of significant importance in terms of promoting deployment of the low energy system, helping reduction of energy use in buildings and cut of the associated carbon emission. This has been achieved through joint effort between EU and China partners under the planned visits and secondments. The process has resulted in great deal of knowledge/technology transfer, PhD and young researcher training, information exchange, and joint events (seminars, meeting and conferences) between the EU and China in the particular areas.