Computational model for a ground coupled space cooling system with an underground energy storage tank

A computational model for determining annual periodic performance of a cooling system utilizing a ground coupled chiller and a spherical underground thermal energy storage tank is developed. An analytical solution for the transient heat transfer problem outside the storage tank is obtained by the application of complex finite Fourier transform (CFFT) technique. Analytical expressions for heat gain to the space and energy consumption of the chiller are acquired, and these expressions are coupled with the transient temperature field problem to obtain computational model. Variation of water temperature in the storage tank is calculated using the transient solution of the problem over an entire year for different soil, chiller, and storage tank characteristics. Temperature profile of earth surrounding the storage tank and the COP of the cooling unit are also investigated under various assumptions and varying system design and operating conditions. The results show that water temperature in the storage tank remains under ambient air temperature during summer months, and thus the proposed ground coupled cooling system should yield higher COP values compared to a corresponding air source system.     

冷却塔风机运行节能之模式与策略的分析

冷却塔风机是整个冷却水系统的核心设备,其运行状况直接关系到系统性能与能耗状况.本文针对国内某办公建筑的冷却塔风机运行状况进行实测,从风机与变频器电耗、冷却塔效率、冷机COP,设备寿命与运行策略的可行性4个方面分析评价了风机运行模式和策略对能耗的影响.     

Energy performance of a cooling plant system using the inverter chiller for industrial building

The purpose of this paper is to clarify energy performance of the cooling plant system in the industrial building using actual measured operating data and numerical simulation analysis. One aspect of industrial buildings is that they have large energy consumption for manufacturing and air-conditioning compared with office and commercial buildings. Some examples of high-efficiency technologies installed in this particular cooling plant system are inverter chillers, integrated cooling towers and a free-cooling system. The inverter chiller which has been put on the market recently is state-of-the-art technology. The maximum COP of the inverter chiller reaches about 18 under certain conditions and integrated cooling towers make lower temperature cooling water as the whole capacity is large. Actual operating data indicates satisfied values for chiller and system COP during the running period and the simulation results show that the cooling plant system can cut down annual electric power consumption by about 48% compared with conventional cooling system.     

Economic benefits of optimal control for water-cooled chiller systems serving hotels in a subtropical climate

A water-cooled chiller system in an air-conditioned hotel can take up about one-quarter of the total electricity consumption and considerable amounts of water in the heat rejection process. This paper evaluates operating cost savings of a chiller system integrated with optimal control of cooling towers and condenser water pumps. A sophisticated chiller system model was used to ascertain how different control methods influence the annual electricity and water consumption of chillers operating for the cooling load profile of a reference hotel. It is estimated that applying load-based speed control to the cooling tower fans and condenser water pumps could reduce the annual system electricity use by 8.6% and operating cost by 9.9% relative to the equivalent system using constant speed fans and pumps with a fixed set point of 29.4 °C for cooling water temperature control. The ways to implement this advanced control for system optimization are discussed.     

某卷烟厂冷水机组运行的性能研究

对某卷烟厂冷水机组运行时进行实验研究,结果表明分别在60%、90%负荷运行时,实际COP值为3.83、4.60,小于该机组的名义工况下5.53的COP值。建议在原空调系统上增加温差控制器和变频器,以控制冷却水泵和冷冻水泵的工作状态,保证该冷水机组的COP在最优化的节能运行状态,从而降低系统的能耗。     

冷却吊顶供水方式对系统运行能耗的影响

通过对冷却吊项运行能耗的计算机动态模拟，分析了供水方式、新风系统形式、冷却塔供冷、制冷机冷水温差等因素对系统能耗的影响，认为采用冷却吊项水系统与新风系统独立的水系统形式，并结合冷却塔自然供冷，节能效果最好。建议生产厂家开发小温差、大流量、低流动阻力的冷水机组，以推动冷却吊项的应用。     

Application of the cumulative exergy approach to different air conditioning systems

The cumulative exergy approach is applied to evaluate two cases with different air conditioning systems. The first case includes three air conditioning systems, one is the gas direct fired air conditioning system, and the other two have air cooled heat-pump chiller and water chiller, respectively; the second case consists of four air conditioning systems, one is the gas direct fired air conditioning system, and the others have centrifugal water chiller, screw water chiller, air cooled water chiller, respectively. The results of the first case show that the air conditioning system with the air cooled heat-pump chiller maybe inferior to that with the water chiller, as the cumulative exergy efficiency of the former is 11.28%, which is less than that of the latter (11.92%). The second case shows that the gas direct fired air conditioning system, whose cumulative exergy efficiency is 14.86%, is better than the system with the air cooled water chiller, whose cumulative exergy efficiency is only 11.56%. The results are different from those of the exergy analysis, indicating that cumulative exergy analysis is an effective method to quantitatively evaluate different air conditioning systems according to resource utilization.     

酒店建筑空调和生活热水方案优化设计

本文利用负荷全年逐时计算数据,引入全寿命周期费效比方法,对北京一家酒店的冷源设计方案的初投资和运行费用比较分析,综合考虑初投资、控制策略、维保难度、运行费用等多方面因素,该项目最终推荐选用水冷冷水机组机＋电热水器的方案。     

北京某商业建筑温湿度独立控制空调系统的全年能耗分析

以北京某一商业建筑为模拟对象,对其空调冷负荷进行模拟,并在此基础上计算普通空调系统和温湿度独立控制空调系统的能耗.经过对能耗的比较和分析表明,温湿度独立控制空调系统的能耗比普通空调系统的能耗降低了16.4%,冷水机组全年平均性能系数提高了13%.结果表明温湿度独立控制空调系统具有很好的应用前景.     

利用盐溶液制备冷水的冷水机组

在间接蒸发冷却装置的基础上，设计了利用盐溶液制备冷水的冷水机组，使得间接蒸发冷却技术能够应用于非干燥地区，并运用了热回收技术达到节能目的。通过对不同室外工况下冷水机组性能的模拟，发现COP对室外空气含湿量最敏感。最后模拟分析了在北京地区使用时此冷水机组的整体性能。     

基于DPSSHP的分布式供能系统在赣南地区的研究

赣南地区城市污水排放量较大,工业废水富含大量余热。发展基于直接式原生污水源热泵(Direct Primary Sewage Source Heat Pump,简称DPSSHP)的分布式供能系统,向建筑供冷供热,将大大降低建筑空调采暖能耗。根据赣南地区实际情况,提出了DPSSHP系统针对不同类型建筑的应用规划。选取了地下水源热泵,大型螺杆式冷水机组+燃煤锅炉,风冷式空气源热泵、DPSSHP,从系统初投资、运行费用、单位面积运行成本等方面进行经济性比较,得出DPSSHP较为经济。     

A study on the energy performance of a cooling plant system: Air-conditioning in a semiconductor factory

This paper will focus on the energy performance evaluation of a cooling plant system in a semiconductor factory. Several energy saving technologies namely: integrated cooling towers, free cooling systems, control of the chilled water quantity, etc., have been adopted to improve efficiency of the cooling plant system. We have collected actual operating data for 2 years and evaluated the performance of chillers’ COP and the whole cooling plant system's COP and they showed satisfactory results even if the thermal load of the factory was about half compared with design phase assumption.

We also have verified each effect of the energy saving technologies through model-based simulation analysis. The annual electric power consumption dropped about 35% compared to conventional cooling plant systems in case of design phase thermal load. And the faulty status operation of the chiller's number control miss occurred while we monitored. Electric power consumption increased about 17% compared to normal status operation at the same period.     

海南某数据中心空调系统设计

结合项目当地具体气候条件,综合对比多种空调系统方案,从节能效果、初投资、运行费用等各方面计算分析,找到适合本项目的 空调系统节能设计.空调设计从系统架构特点出发,利用备用机组的制冷能力,结合磁悬浮机组部分负荷效率高的优点,实际运行时冷水机组全部运行,主机负载率为70％～80％,磁悬浮主机的COP可达15以上,配合冷却塔...     

Energy savings in a building using regenerative evaporative cooling

This paper explores the potential of reducing the annual energy consumption of a central air-conditioned building through advanced evaporative cooling systems. The building considered is a typical three floor library building of a University. The regenerative evaporative cooling technology is coupled with the liquid cooled water chiller system to accomplish the energy conservation objective. Comparisons of the regenerative evaporative cooling are made with simple evaporative cooling to bring out the importance such a system. The well-known building simulation software, TRNSYS is used to carry out the heat load calculations and the dynamic simulations of the building. Annual energy consumptions of different components of the air-conditioning system are estimated for the existing water chiller system as well as for both coupled evaporative cooling systems (simple and regenerative). The annual energy consumptions, the indoor temperature, the relative humidity and the thermal comfort index ‘PMV’ are compared for all the three different air-conditioning systems. The coupling of direct and regenerative evaporative cooling technologies with water chiller system has shown, respectively, 12.09% and 15.69% savings in annual energy consumption of the building, while maintaining PMV between ?1 and +1 for most of the hours in the year.     

直接蒸发冷却及其用于风冷冷水机组的研究

直接蒸发冷却因其节能环保的优点而越来越受到重视,本文建立了基于纸质填料的直接蒸发冷却的数学模型,分析了直接蒸发冷却效率的主要影响因素。研究表明:运用纸质填料时直接蒸发冷却效率可达0.9以上,可实现直接蒸发冷却器的小型化,迎面空气流速和填料厚度对蒸发冷却效率有重要影响。通过对全国15个典型城市的计算分析得出,将直接蒸发冷却与风冷冷水机组联用,对进入风冷冷凝器的空气进行预冷却,可以有效地增加系统的制冷量和减小输入功率,从而提高系统的COP,在我国具有广泛的应用前景。     

浅析联合广场主塔楼空调系统整改

针对联合广场主塔楼具体情况，分析了各种空调系统的适用性，确定采用集中设置冷却水系统的水冷冷水柜机、较好地满足了联合广场整改的要求。     

间接蒸发冷水机组设计开发及性能分析

基于间接蒸发冷却技术设计了高温冷水机组,其驱动源为室外干空气而非电能,冷水机组的理论出水温度可无限接近进口空气的露点温度。建立了数学模型,并提出了系统的串联冷水流程,以更充分地利用室外干空气的能量。合作开发了第一台间接蒸发冷水机组,通过测试得到了实际机组的性能。最后分析了冷水机组作为湿度独立控制空调系统的高温冷源在中国西部及其他地区的应用。     

冷却塔供冷在汽车涂装车间油漆降温系统中的应用

南京某汽车制造厂涂装车间的油漆降温系统,在冬季及过渡季节采用冷却塔供冷。对切换温度、使用时限和能耗进行了分析和探讨。该降温系统使用冷却塔供冷后,减少了全年冷水机组的工作时间,降低了运行成本,取得了良好的经济效益。     

Design of a solar absorption cooling system in a Greek hospital

Air conditioning of buildings is responsible for a large percentage of the greenhouse and ozone depletion effect, as refrigerant harmful gases are released into the atmosphere from conventional cooling systems. The need to implement advanced new concepts in building air conditioning systems is more crucial than ever today.Solar cooling systems (SCS) have the advantage of using absolutely harmless working fluids such as water, or solutions of certain salts. They are energy efficient and environmentally safe. They can be used, either as stand-alone systems or with conventional AC, to improve the indoor air quality of all types of buildings. The main goal is to utilize “zero emissions” technologies to reduce energy consumption and reduce CO₂ emissions.Amongst cooling technologies, absorption cooling seems to have a promising market potential.In this paper, the performance and economic evaluation of a solar heating and cooling system of a hospital in Crete, is studied using the transient simulation program (TRNSYS). The meteorological year file exploited the hourly weather data where produced by 30-year statistical process. The required data were obtained by Hellenic National Meteorological Service.The objective of this study is to simulate a complete system comprised of a solar collector, a storage tank, a backup heat source, a water cooling tower and a LiBr-H₂O absorption chiller. The exploitation of the results of the simulation provided the optimum sizing of the system.     

开式地表水源热泵动态取水温度限值

对于开式地表水源热泵,取水能耗是决定系统节能性的关键因素。在水源热泵机组能耗模型、取水能耗模型等的基础上建立了开式地表水水源热泵系统的能效耦合模型。基于节能率及水泵能耗的规律特点计算得到了不同的冷却塔出水温度下,不同水泵扬程下的动态取水温度限值,建立了开式地表水水源热泵动态取水温度限值的计算方法。并计算得到不同工况条件下的地表水源热泵系统相对传统空调的节能率。