| As energy and environment problems get harsher and harsher, research for the utilization of renewable resource and its development has reached the stage of great urgency. Due to its large-scale distribution, cleanliness and simple applicability, solar energy has attracted recognition to a large extent. By mechanically combining the energy-consuming demand as well as the structural property of buildings with the utilization of solar energy, the integrated technique of solar energy and buildings has overcome such defects as low energy flux density and strong dispersion and has become one of the important ways for the utilization of solar energy. Concerning to the integrated technique of solar energy and buildings, water heating system of solar energy and the heating system of buildings are common ways of the application of solar energy.Active solar air heating system can be applied to space heating of north-oriented buildings, to the ventilation and heating of industrial buildings of large space and depth, and furthermore to the drying of industrial and agricultural products. Since density, specific heat and thermal conductivity of air are relatively small, the photo-thermo transformation efficiency of solar air heater is quite low. In our literature, a double channel solar air heater plated with selective coating material and equipped with parallel fin structure has been introduced. By using selective absorbing coat to repel the radiation loss, while at the same time enhancing the heat exchanging area between air and heat absorber given to fin and dual-channel structure, the heating performance of air has been dramatically improved. We have rigged up an experimental testing platform for air heating and have undertaken experimental research for air heating property of both a single collector and two collectors in series, respectively. The results show that performance of the collector is higher than traditional solar air heater. By arranging two collectors in series, photo-thermo transformation efficiency will slightly drops, resulting in a higher outlet temperature of air. In harsh winter when ambient temperature is approximately0℃, air temperature could reach beyond70℃, which has important sense in terms of space heating and a number of industrial and agricultural applications.A theoretical model for the dual channel solar air heater has been set up. We have carried out a numerical calculation for the thermal property of solar air heater. By comparison and analysis with experimental result, it was shown that the numerical calculation result fits well with that of experiment. With validated theoretical model, we have carried out research into the impact of such elements as the property of absorbing coat on the surface of absorber, the thickness of the insulation layer of backboard and the ratio of the depth of top channel to that of the bottom channel on the performance of solar air collector. Furthermore, we have established the theoretical model for both top channel solar air heater and bottom channel solar air heater. Besides, at one hand, we have taken analysis into the thermo-efficiency and exergy for solar air heaters with three different channel structures, respectively, and at the other hand, we have launched analysis and optimization for air channel depth with three different structures, respectively, based on first thermodynamics law as well as second thermodynamics law.In industrial applications, due to large-scale application of adjoined solar air heating systems, the annual utilization efficiency is relatively small as a result of the mono-function of solar air heater. To resolve this problem, our literature has proposed a dual-function solar collector (DFSC) based on active heating. DFSC could realize air heating and water heating. Heating system fabricated with this kind of module could provide hot air for industrial complex and north-oriented buildings in winter, while supplying hot water requested by industrial process in other seasons, resulted in the prominent raise of both the economy of the system as well as the utilization efficiency of solar energy. The experimental testing platform for air heating and natural-cycled water heating has been rigged up, and theoretical models for both of these two states have been presented. Test results show that DFSC get high performance in both work modes. Analysis and optimization over the inner structure of DFSC for both of the heating modes have been executed, with the help of theoretical model validated by experiments. Furthermore, we have researched the heating property of the compound of air and water and have found that DFSC under compound heating mode could obtain a higher daily heating efficiency than that of mere air heating or mere water heating.Solar water heating system will encounter antifreeze problems in winter. However, such passive heating technique of solar energy for space heating as Trombe wall, or improved Barral-Costantini wall using metal plate for heat absorbing will stay idle for seasons without necessity of heating, what’s more, buildings will be likely to become overheat during the hottest period of summer. In order to have this problem solved, our literature has presented a passive dual function solar collector (P-DFSC) based on passive heating, which could be used for space heating in winter in passive heating mode and water heating for the rest seasons in water heating mode. As a consequence, the annual utilization efficiency and the economy of the system have been magnificently promoted. Relative researches have revealed that, the variation of interior temperatures of buildings equipped with P-DFSC system between daytime and nighttime is quite large. Given to this weakness, our literature innovatively proposed to combine passive heating function of P-DFSC with Kang. Both experimental and theoretical research have been undertaken for the passive heating condition of P-DFSC. Subsequently we have carried out both experimental and theoretical research for the passive heating mode of P-DFSC. Experimental result shows that, subject to passive heating, internal temperature of houses equipped with P-DFSC could reach more than14℃in daytime and more than6℃in night when only the passive heating mode is running. The heat storing property of Kang has made it that the variation of room temperature between daytime and nighttime is slighter. When room temperature is controlled to no less than18℃, P-DFSC room could save electricity amount to approximately3.5kWh in a whole day, in comparison with the reference room. With experiment-validated theoretical model, we have undertaken theoretical research into the performance of passive heating mode of P-DFSC and optimized the depth of air channel. Depth of air channel should be no less than4cm.Finally, with the characteristic of P-DFSC, a theoretical model for window-equipped real building integrated with P-DFSC system has been set up. Besides, theoretical research for the performance of P-DFSC running in different modes in corresponding seasons has been undertaken as well as its impact over buildings. Corresponding result shows that, passive heating mode of P-DFSC could keep the temperature of the room beyond18℃for almost7hours in sunny days of winter. Water heating mode of P-DFSC could decrease thermo-load of the building in overcast days of winter and in summer when only water heating mode is running. |
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