دانلود رایگان مقاله انگلیسی یک سیستم گرمایش و خنک کننده خورشیدی در ساختمان انرژی نزدیک به صفر - هینداوی 2017

The building sector accounts for more than 40% of the global energy consumption. This consumption may be lowered by reducing building energy requirements and using renewable energy in building energy supply systems. Therefore, a nearly zero-energy building, incorporating a solar heating and cooling system, was designed and built in Beijing, China. The system included a 35.17 kW cooling (10-RT) absorption chiller, an evacuated tube solar collector with an aperture area of 320.6 m2 , two hot-water storage tanks (with capacities of 10 m3 and 30 m3 , respectively), two cold-water storage tanks (both with a capacity of 10 m3 ), and a 281 kW cooling tower. Heat pump systems were used as a backup. At a value of 25.2%, the obtained solar fraction associated with the cooling load was close to the design target of 30%. In addition, the daily solar collector efficiency and the chiller coefficient of performance (COP) varied from 0.327 to 0.507 and 0.49 to 0.70, respectively.

5. Conclusions

We presented an initial performance assessment of a solar heating and cooling system in an nZEB building. Values of 13,006 kWh and 38,656 kWh were recorded for the cooling energy supplied by the SHCS and the heat pumps, respectively. Furthermore, a value of 25.2%, which is very close to the design target of 30%, was obtained for the rate of SHCS contribution. The electricity meter revealed that the general energy consumption for cooling, heating, and light from 2014 to 2015 was <23 kWh/m2 . During the intermediate season, the SHCS met most of the load requirements for fresh-air treatment. Although the free cooling concept was adopted, this concept fell short of expectations under actual operating conditions, although the SHCS played an important role in conventional energy consumption reduction.

On sunny days, the daily efficiency of the solar collector and the COP of the chiller varied from 0.327 to 0.507 and 0.49 to 0.70, respectively. The energy requirements must be accurately predicted for a solar heating and cooling system applied in this nZEB building. The load requirements and characteristics of an nZEB differ from those of a conventional building. In the case of a conventional building, the load requirement and changes thereof are affected by outdoor conditions. In the case of an nZEB, changes in the outdoor temperature and solar irradiation have only a modest effect on the cooling load. The main load requirements of an nZEB are to (i) remove heat from equipment, such as personal computers, and (ii) provide energy for fresh-air treatment, which depends on the number of people inside the building. The load characteristics and capacity should be considered during the selection of a solar thermal system. In addition, TES is essential for balancing the load requirement and energy supply of the SHCS in an nZEB.