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• Simulated effects of vegetation on microclimate of different urban blocks in winter. • Simulated effects of vegetation on building heating energy in different urban blocks. • Vegetation brought a building heating load increase of 7.16 % in a sunny day at most. • Vegetation brought a building heating load decrease of 2.80 % in a cloudy day at most. • Offered evergreen urban vegetation strategies for high-density cities in cold region. As an important landscape, the evergreen vegetation is prevailing, even in cold region cities. However, the impacts of promoting vegetation on microclimate and building heating load (BHL) are still inexplicit. This study validated the feasibility of a new-developed coupled model that linked ENVI-met and EnergyPlus, for predicting the microclimate and BHL in winter. The impacts of vegetation configuration changes on the performances of three typical urban blocks in Xi'an, a high-density city in the cold region of China, were then evaluated. When the leaf area index of green lands increased from 0.79 to 4.77 m2/m2, a decrease of 3.27 °C on mean radiant temperature, a decrease of 0.48 m/s on wind speed, and an increase of 0.47 °C on air temperature at the block scale could be observed. To the three blocks, the BHL of thermal zones in the height range of tree canopy increased by 7.16 %, 1.52 % and 3.57 % during a sunny day, and decreased by 2.80 %, 0.55 %, and 0.06 % during a cloudy day maximally. Overall, the evergreen vegetation produced negative impacts on the building energy efficiency of cold region cities. For urban planners, it's advisable to concentrate evergreen plants in high-rise blocks to mitigate such disadvantages. [ABSTRACT FROM AUTHOR]

With the construction of new villages in China, energy-saving technologies for rural buildings have been attracted extensive attention. According to the characteristic of severe cold climate in Hailar, Inner Mongolia, and the structure of rural residential buildings in Taohai Pasture and the energy use customs in these houses, the energy efficiencies of passive energy-saving technologies which are applied to demonstration houses in Taohai Pasture are analyzed. Based on BIM, the calculation models of three types of houses, including the demonstration house applied passive energy-saving technologies, the traditional house and the energy-saving standard model based on local rural residential energy-saving design standard, are established. Then energy simulation software is used to calculate dynamic heating loads of these houses. Furthermore some indexes such as heating load and annual energy consumption per unit building area are compared. The calculated results show that the heating load of the demonstration house in Taohai Pasture is decreased obviously through the passive energy-saving strategies of the thermal insulation of building envelopes, the effective setting of a solar room and the reasonable distribution of indoor functional zones. Compared to the annual heating loads of the traditional house and the energy-saving standard model, that of the demonstration house is reduced about 74.8 % and 28.9%, respectively. The investment increase of the envelope of the demonstration house can be recovered within 11.4 years through the reduction of annual energy use for heating. [ABSTRACT FROM AUTHOR]

This paper proposes a gravity heat pipe exchanger used for cooling the communication base station to replace the air conditioning in winter and transition seasons. Tests were made on the gravity heat pipe exchanger of DHHP 3000 produced by Harbin Dawnhappy Heat Pipe Technology Incorporated. The experiment was performed in order to study the effects of the inlet air flow rate, temperature and the exchanger inclination angle on cooling capacity and efficiency of the heat pipe exchanger. As the indoor and outdoor air flow rate are equal, the cooling capacity of heat pipe exchanger increases with the air flow rate and it also increases with the increase of indoor air temperature and with the decrease of outdoor air temperature; The cooling efficiency decreases with the increase of air flow rate and it gradually reduces with the outdoor air temperature increases from 2 °C to 18 °C. Among the ratios of indoor to outdoor air flow rate of 0.4 kg/s:0.5 kg/s, 0.4 kg/s:0.6 kg/s and 0.5 kg/s:0.6 kg/s, the cooling efficiency of 0.4 kg/s:0.6 kg/s achieves the highest value. In addition, as the inclination angle varies from 5° to 50°, the maximum cooling efficiency can be obtained at angle of 20°. [ABSTRACT FROM AUTHOR]

Water-mediated evaporative cooling systems often suffer from cross-contamination, droplet carryover, and high maintenance costs. This study proposes a novel liquid cooling solution, the hollow fiber membrane-based water cooler (HFMWC), to address these issues. The primary innovation of this study lies in the optimization of key design parameters of the countercurrent HFMWC, aligning them with stringent engineering requirements. Two standard working conditions for wet cooling towers are considered. Numerical modeling and response surface methodology are used to develop regression models correlating six key parameters (water velocity, air/water ratio, fiber length, fiber inner diameter, membrane thickness, and packing fraction) with two performance evaluation indexes (outlet water temperature and consumptive electric power ratio). A genetic algorithm-based multi-objective optimization is employed to obtain Pareto fronts, representing optimal trade-offs between the two indexes. Using the ideal point method, relative optimal solutions are identified, resulting in water temperature drops of 7.56 °C and 13.07 °C, with consumptive electric power ratios of 0.0128 kW h/m3 and 0.0138 kW h/m3 for conditions Ⅰ and Ⅱ, respectively. Most solutions achieve the highest energy efficiency rating while satisfying the design temperature difference. The average deviations between optimized and simulated data for the two indexes are 0.88 % and 3.88 %, demonstrating the reliability of the derived optimal solutions for engineering design. These findings not only offer a promising way to overcome the limitations of traditional evaporative cooling systems, but also contribute to the broader field of sustainable and efficient thermal management technologies. [ABSTRACT FROM AUTHOR]