Demonstration research advances in the development of a central system of heat supply composed of solar cells & thermal pumps for the Olympic Village and attached gyms
A brief introduction of the project: This project is co-sponsored and funded by the CAS, S&T Committee and Bureau of Physical Culture under the Beijing Municipality’s Xicheng District government. It is commissioned for enforcement to the Guangzhou Institute of Energy Conservation, a research arm affiliated to the CAS. An overall target is set for the project: By taking a natatorium as an illustrating example, a year-round system of heated water supply is to be developed with the main heating source coming from the pollution-free solar energy supplemented by thermal pumps in a bid to cater itself to the demands for hot water in living use and supplied to the Olympic Village in the period of the 2008 Beijing Olympic Games. In its blueprint design, the project is noted for its dismissal of an electricity-powered heating system of high-energy consumption as a conventional accessory to a massive hot-water supplying system driven by solar energy. The heating system usually has a fuel- or gas-burning boiler, whose performance is notorious for causing pollution and hidden peril in its normal operation. Instead, our project adopts the up-to-date technology of thermal pumps which can operate normally even in a cloudy day, when solar energy fails to furnish hot water in sufficiently high temperatures. By using the thermal pumps, low luminosity of the sunlight can be utilized to the full, greatly raising the heat-collecting efficiency of the whole system. In addition to a set of smart controls over the heating system, different working conditions might be identified one by one, leading to a system of unmanned controls over a performance of all-round automation. With the enforcement of this project, illustrative cases and exemplary schemes are offered to both the design and construction of the Olympic Village and related tournament grounds as infrastructure facilities of the 2008 Olympiad in Beijing.
Main progresses: All research tasks assigned to the project have been proceeding on schedule. The project’s objective is to build up a hot-water supplying system chiefly powered by an array of solar energy cells and supplemented by thermal pumps. Its designed capacity is 35 tons of hot water per day at the temperature of 50°C for washing, bathing in the daily life of athletes and heating of the swimming pools. The system’s main parts include solar energy collectors, thermal pumps, heat exchange, circulating pumps, a water tank for heat storage and related controls. At present, there are the following research tasks which have been completed or proceeding smoothly:
1). The siting of the project’s demonstration engineering work. The construction site is finally decided to be located in the natatorium at the Yuetan (Moon Altar) Athletic Center situated at the western fringe of the old city of Beijing. Its main heat source is the pollution-free solar energy and thermal pumps are used as the supplementary fixture, forming a new type of hot-water supplying system to serve a gymnasium.
2). Solar energy collectors. They constitute the main part of the system. The solar energy collectors are in the Model of ZL-WF-100/16, composed of 100x2, 000x16 direct current (DC) vacuum glass tubes. Each die block has a light-collecting area up to 4m2. Their outdoors operation features high efficiency, resistance against hailstorm, freeze-proof and in particular, they are installed in a flexible way such as large-area arrays of forced circulation standing on a plat roof or elevated wall in a vertical or horizontal stance. Both the vacuum tubes and heat-absorbing strips may be rotating at will so that the heat-absorbing panels can turn to the sun at their optimal positions.
3) Heat pump: Heat pump is to work as soon as the solar energy supply is inadequate when the sky is overcast or the system operates in night, and it is designed to be well compatible with the solar heating system. When the solar collectors can produce the hot water at 50°C, the heating energy is supplied entirely by the solar collectors. And when the hot water temperature is lower than 50°C, the solar energy makes its way into the evaporator of heat pump as the low-temperature heat source. The condenser of heat pump produces hot water at 50° C or higher. At several days of rainy weather, the surrounding air energy enter into the evaporator as the low-temperature heat source, and the condenser produces the hot water. So the evaporator of heat pump has dual functions.
4) Smart controller: The project adopts auto controller by the smart computer to carry out real-time monitorings and recordings. In order to make the system’s running state optimal, the running modes of the solar-heat pump system are chosen by analyzing various parameters of the system, such as the value of solar radiation, the hot-water temperature in the solar collectors, temperature of the hot-water tank and the natatorium’s water temperature. Through monitoring the temperature in the solar collectors, the surrounding air temperature and running state of the water pumps, the whole system will shun all kinds of irregular performance caused by over-cooling, over-heating or other running malfunctions.
To sum up, the solar-heat pump water-heating system will fully make use of the solar energy and heat energy extracted from surrounding air. The system features the following characteristics:
a) When the whole system is in operation, the clean and pollution-free solar energy acts as the main heat source while the energy extracted from surrounding air plays a supplementary role. The approach not only make use of the reusable energy sources, but also prevents the system from discharging any amounts of exhausted gas, fluid or solid waste into the environment.
b) Another strong point of its performance is higher economic and social returns. In comparison with a oil-burning water-heating systems, the energy-saving is more than 60%, and in comparison with an electric water-heating system; the energy-saving is even higher, reaching 90%.
c) The computerized management of the smart controller leads the whole system always to working at an optimal state and the none-man management is to be realized in the whole system’s performance.
d) The solar collectors, which adopt the direct flow vacuum glass tubes, have higher photovoltaic conversion rate. The anti-freezing fluid in the collectors enables the whole system to have a high capacity against frigid weather and the solar energy may be fully used even in a case when the value of solar radiation is quite low.
Since the project implementation in 2004, the system design and implemental scheme have been basically completed. In March 2004, the solar-heat pump unit was designed and in the ensuing April, all parts and components for the solar-heat pump were manufactured. By now, the whole system is in construction. According to the preset schedule, it is expected that the system’s installation will be finished in the coming August and related measurement, debugging and readjustment will be proceeding in September, the whole system is to be put in normal operation in October.