Quasi-steady state model of an ice rink refrigeration system

A quasi-steady model for the refrigeration system of an indoor ice rink was developed based on a combination of thermodynamic relations, heat transfer correlations and data available in the manufacturer’s catalogue. The system includes five compressors, rejects heat to the ambient air and uses R-22 to keep a stream of brine at a temperature of approximately −9°C. The model has been validated by comparison with measured values and with data from the manufacturer’s catalogue. It was then used to simulate its performance over a typical meteorological year. Results for a representative day include the number of compressors in operation at any given moment, their power consumption, the coefficient of performance (COP) of the cycle and of the system, as well as the heat rejected by the condensers and the corresponding mass flow rate of the cooling air. They show that the evaporation pressure is essentially constant while the condensation pressure varies from about 1600 to 2000 kPa. The COP of the system varies between 1.9 and 2.5. Results for the entire year show that the heat rejected during phase change is approximately four times that due to desuperheating and demonstrates the interest of recovering heat from both processes. Finally, the model is used to illustrate the advantages of a control strategy which limits the maximum number of simultaneously operating compressors to four. This strategy results in a 10% decrease of the energy used by the compressor motors and a 20% decrease of the peak power demand but increases the temperature of the brine at the exit from the chillers by approximately 0.5°C during short periods following the ice resurfacing operations.     

北京天创世缘工程空调设计

该工程空调系统采用冰蓄冷与水源热泵相结合的方式，选用6台三工况水源热泵，夏季水源热泵夜间按制冰工况运行、白天按空调工况运行，冬季利用地下水供暖。比较了常规空调系统与该系统的投资与运行费用，并分别对该工程的冬夏工况进行了调试，结果表明系统节能效果显著。     

蓄冰空调经济性分析软件的研制与应用

介绍了该软件的构成、功能和特点,该软件可完成空调负荷计算、蓄冰系统选择设计、全年能耗及运行费用计算、经济分析评估等任务。使用该软件对重庆某综合建筑的蓄冰空调系统方案进行了计算、并对计算结果进行了分析评估。     

Energy conservation effect of new HVAC system for condominiums with solar collectors integrated with the balcony handrail

Energy consumption in Japan's houses has been increasing rapidly over the past decades. Furthermore, installation of 24-h ventilation systems in houses became mandatory last year, which will probably increase the heating, ventilation, and air conditioning (HVAC) energy consumption in Japan's houses. Regardless of these situations, natural energy utilization to reduce HVAC energy has not spread, especially in condominiums in Japan. In this study, we propose a new HVAC system for condominiums that makes use of solar heat, outdoor cool air by integrating elements in condominiums such as the balcony handrail, the 24-h ventilation system, and under-floor space. As a first step in the development of this system, we carried out experiments and computational fluid dynamics (CFD) studies on a solar heat collector integrated with the balcony handrail to determine its specification and to obtain information on its heat collection performance. As a second step, we calculated dynamic thermal load on a model condominium to evaluate the energy-saving performance and thermal comfort of the proposed system. The calculation results show that the proposed system has a high performance, both for energy saving and thermal comfort.     

Impacts of ventilation strategies on energy consumption and indoor air quality in single-family residences

This report compares the impacts of five different ventilation strategies on the overall energy consumption of superinsulated houses in the Northwestern United States. The strategies examined are: (1) natural ventilation, (2) balanced ventilation with an air-to-air heat exchanger, (3) exhaust ventilation without heat recovery, (4) exhaust ventilation connected to a heat pump to provide space heating, and (5) exhaust ventilation connected to a heat pump to heat domestic water. A modified Transient System Simulation (TRNSYS) residential load model incorporating the Lawrence Berkeley Laboratory (LBL) infiltration model, and a modified TRNSYS domestic hot water model, are used to simulate the energy consumption associated with each strategy. The domestic hot water model is used to determine the amount of useful heat supplied by an exhaust ventilation heat pump as a function of hot water demand schedule and storage tank size. The simulations are made for cities with: (1) a moderate coastal climate, (2) a windy cold climate, and (3) a calm cold climate. They show that total energy consumption (space heat + domestic hot water) can be reduced by 9 to 21% by using mechanical ventilation systems with heat recovery. These savings, compared with energy savings of 18 to 21% achieved by superinsulating the same houses, indicate that the choice of ventilation strategy can have a significant effect on energy consumption. The comparisons also show that for the same effective ventilation rate, houses with mechanical ventilation systems (especially those with exhaust fans) have uniform ventilation and therefore better indoor air quality.     

2002年全国暖通空调制冷学术年会综述

综述了年会盛况，着重报道了有关供热计量收费、用于分户热计量的设计技术方法、不同供热方式，室内空气品质、新风量、置换通风、防排烟，热泵应用、户式中央空调、冰蓄冷与低温送风等热点问题在17个专题讨论会上得出的主要意见。     

Conversion of electric heating in buildings: An unconventional alternative

To decrease the electric energy used for heating buildings it has become desirable to convert direct electrical heating to other heat sources. This paper reports on a study of the possibility of using an unconventional method for conversion to avoid installing an expensive hydronic system. The conversion method combines the ventilation and heating systems and uses air instead of water for distribution of heat within the building, taking advantage of thermal forces and the special properties of gravity currents. Full-scale tests have been carried out in a test apartment inside a laboratory hall where the conditions could be controlled. Temperatures and efficiency of ventilation have been measured to ensure that the demands with respect to thermal climate and air exchange were fulfilled. The results show that it is possible to use the method for heating and ventilation when converting the heating system, but further work has to be done to develop a detailed solution that works in practice.     

碳/玻璃纤维混合编织网增强混凝土电热融冰试验

利用碳/玻璃纤维混合编织网的电热性能,开展了碳/玻璃纤维混合编织网增强混凝土的电热融冰试验研究。结果表明:碳/玻璃纤维混合编织网通电后可以形成稳定的导电加热网络,低电压下即可迅速产生热量使混凝土温度上升,升温过程中电阻率稳定,融冰效果较好。通过分析环境温度、冰层厚度、加热功率等因素对于能耗及融冰效率的影响,为实际应用中的功率控制提供了依据。     

Flow patterns and thermal comfort in a room with panel,floor and wall heating

Thermal comfort aspects in a room vary with different space heating methods. The main focus in this study was how different heating systems and their position affect the indoor climate in an exhaust-ventilated office under Swedish winter conditions. The heat emitters used were a high and a medium–high temperature radiator, a floor heating system and large wall heating surfaces at low temperature. Computational fluid dynamics (CFD) simulations were used to investigate possible cold draught problems, differences in vertical temperature gradients, air speed levels and energy consumption. Two office rooms with different ventilation systems and heating needs were evaluated. Both systems had high air exchange rates and cold infiltration air.     

Optimization of indoor environmental quality and ventilation load in office space by multilevel coupling of building energy simulation and computational fluid dynamics

The fundamentals, implementation, and application of an integrated simulation as an approach for predicting the indoor environmental quality for an open-type office and for quantifying energy saving potential under optimized ventilation are presented in this paper. An integrated simulation procedure based on a building energy simulation and computational fluid dynamics, incorporated with a conceptual model of a CO₂ demand controlled ventilation (DCV) system and proportional integral control of an air conditioning system as the optimization assessment of conceptual model in the occupied zone, was developed. This numerical model quantitatively exhibits energy conservation and represents the non-uniform distribution patterns of airflow properties and CO₂ concentration levels in terms of energy recovery and indoor thermal comfort. By means of an integrated simulation, the long-term energy consumption of heating, ventilation, and air conditioning systems are predicted precisely and dynamically. Relative to a ventilation system with a basic constant air volume supply rate characterized by a fixed outdoor air intake rate from the ceiling supply opening, the optimized CO₂-DCV system coupled with energy recovery ventilators reduced total energy consumption by 29.1% (in summer conditions) and 40.9% (winter).     

Residential air-to-air heat exchangers: Performance energy savings,and economics

Residential energy consumption can be decreased if air infiltration is reduced by constructing houses more tightly. In some cases, however, reduced air infiltration can lead to problems with indoor air quality (e.g., excess humidity and high levels of indoor-generated air contaminants). One solution to this problem is to install a residential air-to-air heat exchanger. The heat exchanger provides a controlled supply of ventilation which counteracts the adverse effects of reduced infiltration. In addition, the heat exchanger recovers much of the energy that would normally be lost when ventilation occurs by air infiltration. Thus, by employing heat exchangers in low-infiltration houses, it is possible to save energy without sacrificing indoor air quality.This paper discusses the performance of residential heat exchangers and summarizes results from tests of several models. It also compares the energy consumed, during the heating season, in low-infiltration houses with heat exchangers, with the energy consumed in typical houses in four cities throughout the United States. For each city, a cost-benefit analysis is performed from the point of view of a home-owner. Houses with natural gas, oil, and electrical heating systems are considered. Our analysis indicates that the energy required to heat ventilation air in homes employing heat exchangers is 5.3 – 18.0 GJ less than the energy required to heat ventilation air in typical homes. In homes with heat exchangers, the heat exchanger's fan system required 2.2 – 3.6 GJ of electrical energy during the heating season. The net present benefit for homes employing heat exchangers, when compared with typical homes, ranged from —$1350 to +$2400 and discounted payback periods ranged from five to over 30 years. The cost-effectiveness of employing heat exchangers was found to be highly affected by climate, type of heating fuel, heat exchanger performance, and ventilation rate.     

Applicability and optimum control strategy of energy recovery ventilators in different climatic conditions

Energy recovery ventilators (ERVs) transfer energy between the air exhausted from building and the outdoor supply air to reduce the energy consumption associated with the conditioning of ventilation air. In this paper, the applicability of ERVs with sensible and latent effectiveness values in a practical range is studied using TRNSYS simulation program. The impact of ERV on annual cooling and heating energy consumption is investigated by modeling a 10-storey office building in four American cities as representatives of major climatic conditions. The results show that heat and moisture recovery can lead to a significant reduction in the annual heating energy consumption (i.e., up to 40%, which is 5% higher than heat recovery). Also, an ERV with the capability of moisture recovery may reduce the annual cooling energy consumption by 20% provided the ERV is properly controlled. Since the un-controlled operation of ERVs during the summer may increase the cooling energy consumption, an optimum control strategy is developed and verified in the paper. This optimum control strategy depends on ERV's latent to sensible effectiveness ratio. For instance, an ERV with equal sensible and latent effectiveness should be operated when either the outdoor enthalpy or temperature is greater than that of the indoor air.     

用于建筑渗风动态能耗分析的气象模型研究

建立了能耗统计的三维(气温、风速、风向)气象模型，并作了详尽的可行性分析计算，编制了通用性的气象统计模型的计算程序。研究结果可用于建筑供暖和渗风全年的动态能耗分析。     

Energy consumption and potential energy savings in old school buildings

Energy and indoor environmental audits of energy consumption and indoor air quality were taken in 24 school buildings in Slovenia. The audits show that these buildings are high energy consumers and have poor indoor air quality, as expressed by 60% of the surveyed pupils. This article deals with energy consumption in the analysed schools. The nominal heating power of boilers, and heat exchangers, which are used in district heating, show a 57% overcapacity. The heat losses of the school buildings are 89% higher than the recommended values. According to our analysis of the possible measures to improve the situation in the school buildings, it will not be possible to ensure rational energy use and good indoor air quality with low investment costs. Should we change from hot-water heating systems and natural ventilation to energy efficient blown air systems with which one device provides the comfort of both heating and air conditioning?     

基于太阳能热利用的生态建筑能源技术

本文介绍了几种基于太阳能热利用的生态建筑能源技术，涉及太阳能利用的建筑物自然通风，太阳能热水系统，太阳能地板采暖，太阳能热泵空调系统，太阳能热水驱动的吸收和吸附制冷系统。并以上海市生态建筑示范项目为例，介绍了其综合能源利用方案。     

某工业园区空调冷热源系统改造

近年来,由于建筑空调冷热源系统设计及配置的不合理而进行改造的项目及情况越来越多,合同能源管理的改造模式也是在这样的情况下产生的。分析了西安市某工业园区空调冷热源系统的现状及存在的问题,并结合园区内可供利用的一次能源、市政能源和可再生能源,以经济性最优为出发点,设计了由土壤源热泵系统、冰蓄冷系统、水源热泵系统和燃气锅炉系统构成的新的空调冷热源系统。通过技术经济性比较得出,改造系统的动态投资回收期小于10年。     

An experimental method for contaminant dispersal characterization in large industrial buildings for indoor air quality (IAQ) applications

Spatial contaminant distribution in large semi-open building areas such as sports arenas, warehouses, atriums, malls and other industrial halls, is critical to estimating exposure, health risks and building energy performance. It is considered a challenge to measure experimentally how effectively the ventilation system removes or dilutes air pollutants in a large open space, taking into consideration the usual non uniformity of the air flow created by local heat and contamination sources, geometrical obstructions and the air distribution system. An experimental method is presented in this paper which can be used for both the experimental evaluation of ventilation effectiveness as well for CFD modeling validation in large open space applications. The developed method which is based on a passive perfluorocarbon tracer gas (PFT) system has been successfully used for the experimental evaluation of ventilation effectiveness in an ice skating arena in the Boston area and for the validation of a developed CFD model for the analysis of the IAQ in ice rink facilities. The method is very easy to use, fast and fairly inexpensive and it does not interfere with human and other activities within the building environment.     

Research on the influence of air humidity on the annual heating or cooling energy consumption

Just taking 960 m² model building with improved envelope for example, this paper studies the influence of outside air humidity on the annual heating and cooling energy consumption and their relative variation rates (RVRs) and the discrepancy between temperature–humidity control (THC) and temperature control (TC) with the same increase of ventilation rates. The research shows that the discrepancy of annual heating and cooling RVRs is significant under different climatic conditions for the same building with the same increase of ventilation rates by the mode of THC. In general, the heating RVRs decline with the increase of average outside air humidity and the cooling RVRs rise with the increase of average outside air humidity. However, annual heating and cooling RVRs are both approximate in different cities under the climatic conditions of approximate annual average air humidity. The annual heating or cooling need by mode of THC is higher than or equal to the corresponding energy consumption by mode of TC and there exists a close relationship between the absolute increment of energy consumption and outside air humidity; furthermore, as the annual average air humidity increases, the absolute increment of annual cooling need increases while that of annual heating need decreases and both have good linear relation.     

基于ANN的绿色办公建筑HVAC系统运行能耗预测

办公建筑中暖通空调系统(HVAC系统)的运行能耗占总能耗比例较高。随着绿色建筑的大力推广,准确预测绿色办公建筑HVAC系统能耗是建筑运行优化的关键。研究以天津市某绿色办公建筑为研究对象,根据绿色办公建筑G中的HVAC系统——地源热泵系统和空调通风系统能耗的实际监测数据,建立了基于人工神经网络的能耗预测模型。研究结果表明,建立的分类多层感知器神经网络预测模型预测精度最好,仅基于气象参数及时间能够精确的预测建筑HVAC系统的小时能耗,为我国绿色办公建筑的设计和运行优化提供科学支持。     

冰蓄冷系统中卤水泵的合理配置和选型

按板式换热器的数量对并联蓄冰系统、按泵的数量对串联蓄冰系统进行了分类，并对常见的蓄冰系统水泵设计方法进行了分析和评价。针对并联单板式换热器系统传统设计方法存在的问题，提出了泵的改进设计方法；对于串联系统，则提出采用制冷机旁通、多级泵和变频泵的方法使系统配置更加合理。