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The evacuated tube solar collector with auxiliary electric heater (ETCAEH) was presented for rural heating in this study. The examined building heating system with evacuated tube solar collector was designed and constructed in Jinan city, china. The aim of this study is to analyze the feasibility of building heating system presented. Thermal performance and economic analysis of ETCAEH for rural heating were investigated. The results show that the heating room indoor air temperature can meet heating demand by adopting ETCAEH. Furthermore, ETCAEH used in rural area has applicative enough for their advantages in economy by comparing with coal-fired boiler and air conditioning. It is said that this study will provide guidance for designing and economic feasibility of ETCAEH used in building heating.

In this paper, based on the study of the effect of indoor natural ventilation, application of earth-air heat exchanger cooling technology in an office was investigated. Taking an office building in Jinan City as an example, this research analyzed the performance of interactions between earth-air heat exchanger cooling technology and building indoor thermal environments. Indoor thermal environment was analyzed with numerical simulation of computational fluid dynamics, the Airpak software was applied for numerical calculation to gain the indoor temperature field, velocity field and the distribution of the PMV index. In addition, energy utilization efficiency was also analyzed in this paper; results showed that reasonable airflow organization is a significant content in airflow design of office rooms under the small temperature difference of earth-air heat exchanger conditions. This will provide basic reference for design of earth-air heat exchanger cooling system.

In this study, a flat plate solar collector with dual-function (FSDF) embeddable in a hybrid solar drying system is proposed and constructed. In the present drying system, air outlet temperature of FSDF is controlled within the suitable drying temperature range. Thereby the efficiency of solar energy utilization and the quality of dry product can be improved. This study has revealed, for the first time, solar drying air temperature can be controlled by adopting operation strategy based on FSDF. The operation strategy, thermal performance and economic analysis of flat plate solar collector with dual-function hybrid dryer (FSDFHD) are investigated. A detail mathematical modelling is developed to calculate the thermal parameters of FSDF. Performance test of FSDF were also carried out in the September of 2017. The results show that there is a good agreement between the simulated and experimental values of these parameters. For the glass cover, absorber plate and outlet air temperature, the root mean square deviation (RMSD) value is 8.9%, 11.9% and 10.5% respectively. The range of maximum heat collecting efficiency of FSDF is 32.5%–50.8% for three different heat collecting modes. The range of heat loss coefficient of FSDF is about 2.5–6.2 W/(K m2). In addition, operation strategy of FSDFHD all year round is given and analyzed through case study. The solar fraction and energy distribution of FSDFHD can be calculated at any day of the year. Finally, economic analysis is conducted to study the application of FSDFHD in china. The results show that FSDFHD has applicative enough for their advantages in economy with the help of judgement criteria of the present value of the cost and the annual cost. Thus, this study can provide theoretical basis for designing and operating strategy of FSDFHD in drying agricultural products.