变风量空调系统设计冷负荷计算方法的探讨

指出了在空调房间末端冷量可调的变风量空调系统,对制冷设备客量选择具有很大影响的室内冷负荷应当以空调建筑中所有房间逐时冷负荷的综合最大值为依据。并以旁通型变风量集中空调系统为例,对空调系统设计冷负荷的计算方法进行了分析讨论。     

主控室空调系统动态冷负荷跟踪试验研究

核电站主控室空调系统能够为主控室操纵员提供舒适的工作环境,对于核电站的正常运行意义重大。本文通过主控室空调系统启动时主控室温度调节试验,研究了主控室动态冷负荷跟踪调节系统的控制精度和调节速度,试验结果满足设计预期,符合运行要求。     

空调冷负荷计算中选取冷负荷系数的方法

分析在计算灯光照明及人员显热散热引起的冷负荷中选取冷负荷系数的方法，为正确计算冷负荷提供依据.     

大型超市空调冷热源选择的对比研究

本文研究了大型超市建筑夏季空调冷负荷的主要影响因素,并以上海市某一大型超市建筑为例,分析其夏季空调负荷的分布规律,并针对不同的冷热源选择方案,结合超市建筑的空调负荷特点,提出了多种空调冷热源方案的适用性,可为大型超市空调冷热源的设计提供参考.     

基于正交实验法分析影响游泳馆类建筑空调冷负荷的因素

利用正交实验的方法,通过能耗模拟软件Dest-c对沈阳市某戏水大厅空调冷负荷进行模拟分析,比较外墙传热系数、屋顶传热系数、外窗类型、人员密度、室内设计温度、相对湿度、散湿量等7个因素对建筑模型的影响。通过统计分析软件Spss16.0进行极差分析、方差分析得出最优方案,并比较各因素、各水平的显著性。     

基于动态负荷跟踪的水蓄冷空调系统节能研究

以中原经济区职业教育培训学校水蓄冷空调系统为研究对象,针对实际工程案例,采用配合蓄冷空调动态负荷的跟踪监测系统,相比传统空调系统日平均节约电费为12 704.60$,可转移非低谷电量41.28%。通过对系统负荷进行动态跟踪监测,分析了空调输出负荷与实际所用负荷匹配技术的相关性,以期合理调控空调区域负荷需求、适时提供制冷量,旨在实现系统节能降耗和减少实际开机容量,为类似空调系统的工程设计、运行及空调动态负荷监测的研究提供参考和借鉴。     

办公楼楼板地面及底面造隔热层以降低间歇空调冷负荷的节能评估

以简化理论计算了间歇空调的办公楼一周的降负荷及附加冷负荷,提出了楼板地面及底面造隔热层以降低楼板向室内放热及在周六、周日的吸热量,简化计算了典型夏日可节省日间空调平均耗冷量约10W/m2.以周一为例,需为一般地毡式地面办公楼单元增加室内设备冷却容量约18W/m2,造楼板隔热层后则只需增加约8W/m2.周一清早降负荷时问...     

水蓄冷空调设计方法探讨

叙述了在各种气候条件下不同形式规模和用途的建筑中，以水蓄冷空调冷负荷特性为出发点的3种可能性，设计了多种技术方案，分析了各种水蓄冷空调系统的技术经济效益，提出了针对各种不同电价政策可选择的方案。     

建筑物冬季供暖空调逐时负荷

对华北地区冬季建筑物南外窗的逐时日射得热和相应的室内空气得热进行了分析和计算,结果表 明在大部分的日照时刻南外窗(玻璃幕墙)的逐时日射得热及室内空气逐时得热已超过其本身的逐时负 荷。中央空调系统应采用合理的空调分区和有效的调控设备利用这部分热能,以避免造成建筑物冬季 南向房间过热和能源浪费。     

Feasibility study on novel hybrid ground coupled heat pump system with nocturnal cooling radiator for cooling load dominated buildings

When the ground coupled heat pump (GCHP) system is utilized for air conditioning in cooling load dominated buildings, the heat rejected into ground will accumulate around the ground heat exchangers (GHE) and results in system performance degradation. A novel hybrid ground coupled heat pump (HGCHP) system with nocturnal cooling radiator (NCR) works as supplemental heat rejecter is proposed in this paper to resolve this problem. The practical analytical model of NCR and novel HGCHP system are established. The computer program based on established model is developed to simulate the system operation performance. The novel HGCHP system is designed and simulated for a sample building located in Hong Kong, and a simple life cycle cost comparisons are carried out between this system and conventional GCHP system. The results indicate that it is feasible to use NCR serves as supplemental heat rejecter of the novel HGCHP system for cooling load dominated buildings even those located in humid subtropical climate areas. This novel HGCHP system provides a new valuable choice for air conditioning in cooling load dominated buildings, and it is especially suitable for buildings with limited surface land areas.     

Assessment of a modified method for determining the cooling load of residential buildings

Cooling load calculations are essential in sizing air conditioning system equipment. In designing energy, efficient and renewable energy sourced cooling systems for buildings, it is important to have the exact values of cooling loads and seasonal cooling demands of buildings. In this paper new assessment method for more precise determining of cooling loads and seasonal cooling demands of residential buildings are developed, which are necessary for right solutions of cooling efficiency problems. Comparing to the method of ASHRAE, example and other methods it provides more correct results. Application of suggested method provides better accuracy in assessment of cooling loads especially for seasonal aspects, as they take into account the impact of more factors.     

Ventilated facades energy performance in summer cooling of buildings

The use of ventilated facades and roofs can help to reduce summer thermal loads and, therefore, the energy consumption due to air-conditioning systems. This paper discusses a simple analytical method for the calculation of the energy saving achievable by using ventilated facades in which the air flow inside the air duct is due to stack effect. Two particular cases of outstanding importance are investigated. The first in which the inner masonry wall is given, and the air duct and the outer facing have to be optimized. The second in which the outer facing is given, and the inner masonry wall and the air duct have to be optimized. The first case can occur in existing buildings renovation, while the second case can occur during the design process. Finally, the influence of the variation of some quantities necessary for calculation on the energy performance of ventilated facades is investigated. In particular, the energy performance of such facades results to be strongly influenced by the air duct width, the insulating material distribution, the solar radiation intensity, the wall outer surface thermal resistance and the roughness of the slabs delimiting the air duct.     

A case study for influence of building thermal insulation on cooling load and air-conditioning system in the hot and humid regions

Ensuring the effective thermal insulation in regions, where the cooling requirement of building with respect to heating requirement is dominant, is very important from the aspect of energy economy. In this study, the influence of thermal insulation on the building cooling load and the cooling system in case of air-conditioning by an all-air central air-conditioning system was evaluated for a sample building located in Adana, based on the results of three different types of insulation (A, B and C-type buildings) according to the energy efficiency index defined in the Thermal Insulation Regulation used in Turkey. The operating costs of the air-conditioning system were calculated using cooling bin numbers. Life-cycle cost analysis was carried out utilizing the present-worth cost method. Results showed that both the initial and the operating costs of the air-conditioning system were reduced considerably for all three insulation thicknesses. However, the optimum results in view of economic measurements were obtained for a C-type building. The thickness of thermal insulation for the buildings in the southern Turkey should be determined according to the guidelines for a C-type building.     

Heat transfer effect on the specific cooling load of refrigerators

The maximum possible specific cooling load that can be obtained from two-heart-reservoir refrigerators with a set of high-temperature heat sinks and low-temperature heat sources is analyzed. The refrigerators considered in this paper include (1) externally and internally reversible, (2) externally irreversible and internally reversible, (3) externally reversible and internally irreversible and (4) externally and internally irreversible refrigerators. The irreversibilities are assumed to be caused by heat transfer only. The specific cooling load, defined as the cooling load per unit total heat-exchanger surface area, is adopted as the objective function for the refrigerator performance analysis in this paper.     

Experimental results of different control strategies in a solar air-conditioning system at part load

In this article, different control strategies used in a solar cooling installation are presented and compared, publishing real working data from three summer periods, with the system working at part load.The facility consists of two solar fields that feed a heating system during the winter and a 35 kW Li-Br absorption chiller during the summer period to cool part of an office building.The improvements obtained using control based on critical radiation and a variable flow mass have been compared on the solar plant with a conventional constant flow control. In the same way, the improvements obtained in the yields of a cooling production plant have been compared when programming three different controls: the first one with fixed flow masses, the second adapting the temperature on the condenser as a function of the generator temperature (constant flow mass), and the third adapting the condenser temperature and the flow mass on the generator as a function of the system loads.     

Improvements of building envelope using passive cooling techniques to reduce the cooling load in hot‐dry regions

In developed countries, the buildings are responsible for massive energy consumption. When the construction is based on the use of nonsustainable methods, the buildings were dependent on the active systems, for ensuring a maximal indoor comfort. This has increased energy consumption and related greenhouse gas emissions. In this study, a reduction technique of cooling load and power consumption in buildings is proposed. This technique involves the combination of three passive cooling techniques, thermal insulation, phase change materials (PCMs), and electrochromic double glazing. These techniques are applied through simulation software “DesignBuilder” to a building envelope model in various areas like walls, roofs, and glazing. For this purpose, a standard building model is compared with 16 other cases that incorporated the passive cooling techniques for determining the effectiveness of the proposed method. The results show that a combination of PCMs, thermal insulation, and double glazing can reduce the cooling load from 70.37 to 50.53 kW and the energy consumption from 1.51 to 0.90 kWh/m ².     

Cooling load reduction of building by seasonal nocturnal cooling water from thermosyphon heat pipe radiator

In this study, a concept of using thermosyphon heat pipe to extract heat from water in a storage tank to generate cooling water was proposed. Heat pipe condenser was attached with an aluminum plate and acted as a thermal radiator while its evaporator was dipped in the water storage tank. Cooling water in the tank could be produced during the nighttime and used to serve the cooling load in a room during the daytime. A heat transfer model to calculate the water temperature and the room temperature during both the nighttime and daytime was developed. The input data were ambient temperature, dew point temperature, area of the radiator, volume of cooling water and room cooling load. The experiment was setup to verify the heat transfer model. A 9.0 m² tested room with six cooling coils, each of 0.87 m² was installed at the ceiling, was constructed along with the 1.0 m³ water storage tank. A 500–2000 W adjustable heater was taken as an artificial load inside the room. A 6.36 m² radiator is installed on a 45° tilting roof of the tested room. The simulated results agreed very well with those of the experimental data. With the developed model, a simulation to find the sizing of the radiator area and the volume of cooling water for cooling water production during winter of Chiang Mai, Thailand was carried out. The cooling water was used for cooling during summer in an air‐conditioned room with different cooling loads. The parameters in terms of room temperature, radiator area, volume of cooling water, cooling load and UA of cooling coil were considered to carry out the percent of cooling load reduction. Copyright © 2009 John Wiley & Sons, Ltd.