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Abstract: This paper reports the evaluations of energy efficiency, plume potential as well as plume control of a huge chiller plant using water-evaporative cooling towers for heat rejection for a super high-rising commercial office building in a subtropical region of Hong Kong. The evaluations were carried out in a dynamic Transient Simulation Program (TRNSYS)-based simulation platform using alternative control strategies including set-point control logics of the supply cooling water temperature and cooling tower fan modulation control methods as well as different number control means of cooling towers. The results show that different control strategies have significant effects on the energy efficiency of the chiller plant. The quantification of the energy efficiency demonstrates significant energy-saving potential by using advanced technologies for implementing optimal control strategies in this cooling system. The results also reveal that the plume may occur frequently in spring and summer seasons and occasionally in other months due to the odd subtropical weather conditions. Control strategies also have significant effects on the frequency of the plume occurrence. The effective energy efficiency control and effective plume control using wet–dry (i.e., hybrid) cooling towers are also discussed. [Copyright &y& Elsevier]

Reports on the greenhouse gas (GHG) emissions from energy consumption activities in the iron and steel industry in East China. Concern on the concentration of carbon dioxide and other GHG in the atmosphere; Consumption of solid fuel by the industry; Percentage of energy consumption and emissions; Discussion of mitigation appropriate to the energy consumption and emissions.

Abstract Aerogel insulating panels (AIPs) exhibit extensive prospects for application in aerospace, industry and buildings as excellent energy-saving thermal insulators owing to their ultra-low thermal conductivity. This work aims to numerically and experimentally investigate the thermal performance of AIPs in building energy efficiency. The AIPs were prepared and used as an insulation layer in an insulating cell. Three insulating cells with three different insulating materials as the insulation layer were prepared to measure and comparatively analyse their thermal performances. A resistance-capacitance thermal network model to predict the thermal performance of the insulating cells was developed and validated with the experimental data. The thermal indices of cells, i.e. the time lag, decrement factor and daily heat loss, were explored under periodic disturbances of exterior air temperature. Furthermore, the thermal performance of AIPs for exterior walls was predicted by adopting the typical wall structure in the hot summer and warm winter zone of China. The results showed that the AIP wall has decreases of ∼20% and ∼40% in the fluctuation amplitude of the internal temperature and heat flow, respectively, compared with the traditional insulating walls. Highlights • A method to indicate thermal performance of AIP for energy efficiency is proposed. • Three insulating cells with EPS, GF and AIP are prepared and compared. • AIP cell shows twice time lag, 40% less decrement factor and 35% less daily heat loss. • AIP wall has ∼20% and ∼40% decreases in amplitudes of temperature and heat flow. [ABSTRACT FROM AUTHOR]

Effective evaluation on the thermal performance of envelope plays an important role towards the reduction of energy consumption for space cooling and heating. In order to calculate the energy consumption for cooling and heating and assess the whole energy efficiency of envelop designs, a new evaluation index on energy and thermal performance for office building envelop (EETPO) is put forward. Three cities of Shenyang, Wuhan and Guangzhou in China are selected for EETPO analysis, which represent the cold zone, hot summer cold winter zone and hot summer warm winter zone, respectively. The regression equations between EETPO and energy use for cooling/heating are studied in three cities, illustrations indicate that the regression lines fit extremely well and the algorithm is accurate and simple. According to the compulsory indices stipulated by standard (GB50189-2005), the maximum allowable values of EETPO are determined in three cities, the maximum EETPO c in cooling period is 1.750 W/m 3 K in Wuhan and 1.733 W/m 3 K in Guangzhou, the maximum EETPO h in heating period is 0.200 W/m 3 K in Shenyang and 0.414 W/m 3 K in Wuhan. This index and energy use calculation method can help designers to evaluate the whole energy and thermal performance of the proposed envelopes and analyze energy saving effects for different energy conservation measures. [ABSTRACT FROM AUTHOR]

Abstract: Heat pumps could be used to produce hot water for hybrid cooling towers for preventing the occurrence of plume in subtropical regions. The evaporative side of the heat pump system could be arranged either at the inlet side or at the outlet side of these cooling towers for cooling down the cooling water temperature. Alternatively, the evaporative side of the heat pump system could also be arranged at the evaporative side of chillers to reduce return chilled water temperature and therefore to reduce the cooling load of chillers. This study presents the evaluation of the impacts of these three arrangements of the heat pump system on the plume control performance and the energy performance in a large-scale chiller plant in Hong Kong. The performance prediction and evaluation of the chiller plant and the plume abatement system were conducted on a dynamic simulation platform. The results show that these three arrangements have almost the same plume control performance with sufficient plume control capability. The results also show that the arrangement of the evaporative side of the heat pump system for cooling down return chilled water temperature has much better performance that the other two arrangements for improving the overall energy efficiency. [Copyright &y& Elsevier]