对日有用得热量试验条件的实验研究

通过对多台家用太阳热水系统多次单天热性能测试结果的分析,得到日有用得热量的测量误差,以及日有用得热量与太阳辐照量H、日平均环境温度与开始温度的温差(tad-tb)的关系。通过讨论认为在试验条件中将太阳辐照量H降至16MJ/m2对测试结果无影响,测试时可考虑适当放宽tad的范围,通过限制(tad-tb)值的大小来减少tad变化对q17的影响,增加有效的检测天数。     

浅谈家用太阳热水器热性能测试

如何评价与检测家用太阳热水器的热性能呢？国家质量监督检验检疫总局于2002年4月28日发布了国标GB／T 18708—2002《家用太阳热水系统热性能试验方法》，通过此试验方法可得到太阳热水器能量输入一输出曲线图，它全面系统地反映了在不同的季节、不同的太阳辐照量条件下的太阳热水器能量输入一输出特性，实现了我国太阳热水器产品的热性能试验与国际接轨。     

家用太阳热水系统的热性能试验方法--GB/T 18708-2002国家标准介绍

我国自改革开放以来，经济发展迅速，人民生活水平日益提高，真空管太阳集热器、太阳热水系统产品的生产水平和数量不断提高，我国已成为世界上真空管太阳集热器、太阳热水系统产品的主要生产与使用国家。２００２年４月２８日国家质量监督检验检疫总局发布了GB／T１８７０８－２００２“家用太阳热水系统热性能试验方法”。通过试验给出太阳热水系统的得热量曲线与方程，可以预测该太阳热水系统在使用地区的全年得热量（MJ）；给出了太阳热水系统贮热水箱的平均热损系数（W／K）。新国标的实施，会促进我国太阳能热利用事业的发展。太阳…     

几种全玻璃真空集热管太阳热水器日有用得热量的对比试验

一前言 根据GB/T 19141,日有用得热量是评价太阳热水器热性能的一个重要指标.对于直插紧凑式全玻璃真空集热管太阳热水器(以下简称热水器),影响热水器日有用得热量的主要因素有:真空集热管的光-热性能和热水器的结构设计.热水器的结构设计包括:相邻管中心线的间距,一根集热管"带"水量以及管内的贮水量;联集管的结构;有无反射器.     

家用太阳热水系统标准探讨

家用太阳热水系统性能检测的国家标准主要有GB/T 18708-2002、GB/T 19141-2003,因测试目的不同,两个标准之间以及与其他各相关标准之间存在一些差异,针对热性能测量系数对各相关的国内外标准进行对比分析,对家用太阳热水系统某些参数测量提出改进建议。     

先进实用的汽轮机试车站

为配合燃气-蒸汽联合循环电站机组的开发，南汽集团改建了汽轮机试车台，整套装置先进实用，系统设计特色鲜明，能适应多工况试车。     

Solar heat gain factors and heat loss coefficients for passive heating concepts

The concept of solar heat gain factor has been introduced for calculating the net energy gain of passive heating elements and other components of a building as a result of incident solar radiation. For passive heating concepts (namely, the direct gain, mass wall, water wall, Trombe wall, and solarium), exact analytical expressions have been obtained for the solar heat gain factors and the corresponding overall heat loss coefficients. These will allow a building designer to calculate immediately the overall heat gain/loss in a building. Numerical calculations have been done for typical values of solar radiation and ambient temperature of typical climatic conditions in India. The method has been compared with the other methods reported in the literature so far. A good comparison is found between the earlier methods and the method of using solar gain factors and the corresponding heat transfer values.     

提高太阳热水器得热量的方法

热水器得热量及热损系数是衡量太阳热水器优劣的主要技术指标。在目前的技术水平下,热损系数已经相当小,因此,提高单位面积有效得热量就成为进一步改善太阳热水器性能的一个主要途径。笔者在查阅部分文献后,主要从选择性吸收涂层、反射板、玻璃及热水器结构等方面着手,归纳了几种能有效提高太阳热水器单位面积有效得热量切实可行的方法。     

Reversible low solar heat gain windows for energy savings

Summer cooling loads in buildings can be reduced with windows of low solar heat gain coefficients (SHGC). Such windows are often double glazed with the exterior pane tinted or selectively absorbing. They reject part of the absorbed solar radiation to the environment, reducing the solar heat gain. This effect is undesirable in the cold season. However, the same window installed in reverse, i.e. turned by 180°, has a significantly higher SHGC. Thus, windows that can be reversed according to the season will both reduce summer heat gains and collect much of the beneficial solar radiation in winter. This paper investigates the energy savings achievable by reversing equator-facing windows for the duration of the cold season as opposed to leaving them in the “summer position”. Candidate climates in which these savings may be significant are identified. By means of a computer simulation, seasonal energy savings are predicted for a model room with reversible, low SHGC, windows. The results indicate that for suitable climates, significant savings are achievable.     

Residential building envelope heat gain and cooling energy requirements

We present the energy use situation in Hong Kong from 1979 to 2001. The primary energy requirement (PER) nearly tripled during the 23-year period, rising from 195,405 TJ to 572,684 TJ. Most of the PER was used for electricity generation, and the electricity use in residential buildings rose from 7556 TJ (2099 GWh) to 32,799 TJ (9111 GWh), an increase of 334%. Air-conditioning accounted for about 40% of the total residential sector electricity consumption. A total of 144 buildings completed in the month of June during 1992–2001 were surveyed. Energy performance of the building envelopes was investigated in terms of the overall thermal transfer value (OTTV). To develop the appropriated parameters used in OTTV calculation, long-term measured weather data such as ambient temperature (1960–2001), horizontal global solar radiation (1992–2001) and global solar radiation on vertical surfaces (1996–2001) were examined. The OTTV found varied from 27 to 44 W/m² with a mean value of 37.7  W/m². Building energy simulation technique using DOE-2.1E was employed to determine the cooling requirements and hence electricity use for building envelope designs with different OTTVs. It was found that cooling loads and electricity use could be expressed in terms of a simple two-parameter linear regression equation involving OTTV.     

Thermal network predictions of the daily temperature fluctuations in a direct gain room

This paper studies the daily temperature fluctuations in a direct gain room measuring 6.1 × 4.57 × 2.44 m³ (20 ft × 15 ft × 8 ft). The room is assumed to have losses on three faces and 8.36 m² (90 ft²) of south glazing. Let r denote the ratio of the surface area of the mass wall to the area of the south facing glazing. The effect of r on mass walls 10.16, 20.32 and 30.48 cm (4, 8 and 12 in.) thick was determined for values of r equal to 1, 2, 4, 8 and 11.1. The temperature and solar insolation values for a typical January day in Nebraska were duplicated thirty consecutive times and were used for the weather data input to the modeling program. Using thirty consecutive like days has the advantage of damping out the transient solution to the point where it is negligible. It was found that for each thickness of wall, the temperature fluctuations over a day decrease as r increases, and it was also found that for a fixed value of r, the daily temperature fluctuations decrease as the wall thickness is increased. These results are consistent with those reported by Mazria.In addition cloudy day storage was considered for both the 10.16 and 20.32 cm (4 and 8 in.) walls, with r fixed at 4, runs were made with 20, 33, 50 and 100 per cent cloudy days. The results are presented in graphical form and indicate a rapid recovery of the system in most cases.     

Development of an analytical model useful for micro heat engine analysis

A general endo-reversible heat engine model is presented for a combustion driven system. It is composed of a Carnot heat engine and a combustor operating at a specified temperature. The model is inspired by past work on ideal engine/combustor systems and the need for an analysis technique incorporating heat losses suffered by all practical micro engines. This latter consideration results from the necessary structural connections existing between the hot and ambient temperature sections of the engine. In the model developed here, a counterflow heat exchanger provides this structural connection while recovering a portion of the sensible heat in the exhaust flow. A thermal shunt resistance to the surroundings is used to account for conductive heat loss. Finally, a high degree of idealization is employed to obtain a closed form analytical solution for the operating conditions of the engine/combustor system which, in this case, is assumed to be at the maximum power point of the device.     

太阳能集热器动态测试方法简介

本文介绍了目前国际上影响较大的几种太阳能集热器的动态测试方法的原理、实验装置、测试步骤,分析了它们在实验条件要求、实验步骤、应用范围、数据处理方法和精度等方面的差别。