Yong Guan

The use of renewable energy for food and vegetable production is a potential sustainable method to reduce fossil energy consumption. Chinese solar greenhouses (CSGs) are horticultural facility buildings in the northern hemisphere that use solar energy to produce off-season vegetables in winter. The north wall heat storage and release capacity of CSG has a significant impact on the indoor thermal–humidity environment. However, common traditional solar greenhouses commonly have problems such as insufficient heat storage and release, thick temperature stability zones inside the walls, and inability to dynamically regulate the entire greenhouse environment. Therefore, a novel active–passive heat storage wall system (APHSWS) incorporating phase change materials has been developed to promote the thermal performance of the CSG and its internal temperature of the thermal storage wall in this paper. Through experimental and simulation methods, the heat storage and release of the APHSWS and its impact on the greenhouse environment are investigated. The findings indicate that the APHSWS has increased the wall heat storage and release capacity, compared to the ordinary greenhouse without the APHSWS, in three typical weather conditions in winter (i.e., sunny, overcast, and cloudy); the average temperature of greenhouse with the APHSWS has increased in indoor air temperature, wall surface temperature, and soil surface temperatures of 1.58–6.06 °C, 2.71–6.58 °C, 0.91–6.39 °C, respectively; and during the experiment, the greenhouse with the APHSWS has a monthly average daily effective accumulated temperature of 1.39 times, 1.18 times, 0.60 times, and 0.20 times that of the ordinary greenhouse without the APHSWS from December to March of the next year, respectively. Under typical sunny conditions, the greenhouse wall heat storage capacity increased by 1.59–2.44 MJ/m² and the heat release capacity increased by 0.97–1.17 MJ/m². At the direction of wall thickness, the temperature at each point inside the wall with the APHSWS is always higher than that of ordinary wall without the APHSWS. In addition, the operating cost of the APHSWS in winter is analyzed.

Under dehumidifying conditions, the condensed water will directly affect the heat transfer and resistance characteristics of a fin-and-tube heat exchanger. The geometrical form of condensed water on fin surfaces of three different fin materials (i.e., copper fin, aluminum fin, and aluminum fin with hydrophilic layer) in a fin-and-circular-tube heat exchanger was experimentally studied in this paper. The effect of the three different fin materials on heat transfer and friction performance of the heat exchanger was researched, too. The results show that the condensation state on the surface of copper fin and aluminum fin are dropwise condensation. The condensation state on the surface of the aluminum fin with the hydrophilic layer is film condensation. For the three different material fins, increasing the air velocity (u_a,in) and relative humidity (RH_in) of the inlet air can enhance the heat transfer of the heat exchanger. Friction factor (f) of the three different material fins decreases with the increase of u_a,in, however, increases with the increase of RH_in. At the same u_a,in or RH_in, Nusselt number (Nu) of the copper fin heat exchanger is the largest and Nu of the aluminum fin with hydrophilic layer is the smallest, f of the aluminum fin heat exchanger is the largest and f of the aluminum fin with hydrophilic layer is the smallest. Under the identical pumping power constrain, the comprehensive heat transfer performance of the copper fin heat exchanger is the best for the studied cases.

Despite the rapid growth in the uptake of renewable energy technologies, the educational profile and the skills gained at University level do not always comply with the practical needs of the organisations working in the field. Furthermore, even though the residential sector has very high potential in curbing its CO2 emissions worldwide thus meeting the challenging goals set out by the international agreements, such reduction has been limited so far. Within this context, the ‘Skybelt’ project, co-funded by the EU under the framework of the Erasmus + programme aims at enhancing in several Universities of Asia and Europe the engineering skills of students of all level for application of sustainable renewable energy solutions in the built environment. With the target of increasing the employability of graduates and the impact of the project, a survey on the labour market needs for specialists with enhanced knowledge and skills in the topic of the project has been conducted in the related Asian countries. Hence, relevant industries, labour market organisations and other stakeholders have been interviewed and the main results of this analysis is reported in the present paper. As first outcome of this activity, the obtained results have been considered in the selection of the modules to be improved according to a student centred study approach.