蒸发冷却技术在我国非干燥地区的应用研究

介绍了蒸发冷却的原理与种类 ,通过分析计算 ,得出除湿蒸发冷却技术在我国非干燥地区存在应用的可行性。采用该技术不但可以保护环境 ,提高室内空气品质 ,在有余热废热利用的场合 ,还能大大节省系统耗电量 ,起到很好的节能效果。建议应在我国推广应用这一技术并制定相应的标准规范。     

Experimental study of a direct evaporative cooling approach for Li-ion battery thermal management

A desirable operating temperature range and small temperature gradient is beneficial to the safety and longevity of lithium-ion (Li-ion) batteries, and battery thermal management systems (BTMSs) play a critical role in achieving the temperature control. Having the advantages of direct access and low viscosity, air is widely used as a cooling medium in BTMSs. In this paper, an air-based BTMS is modified by integrating a direct evaporative cooling (DEC) system, which helps reduce the inlet air temperature for enhanced heat dissipation. Experiments are carried out on 18650-type batteries and a 9-cell battery pack to study how relative humidity and air flow rate affect the DEC system. The maximum temperatures, temperature differences, and capacity fading of batteries are compared between three cooling conditions, which include the proposed DEC, air cooling, and natural convection cooling. In addition, a DEC tunnel that can produce reciprocating air flow is assembled to further reduce the maximum temperature and temperature difference inside the battery pack. It is demonstrated that the proposed DEC system can expand the usage of Li-ion batteries in more adverse and intensive operating conditions.     

Recent researches in indirect evaporative cooler V: relative thermal performance of buildings coupled to direct and indirect evaporative cooler

A mathematical model has been developed to evaluate the relative thermal performance of a building coupled with an indirect or direct evaporative cooler. Using periodic analysis for taking into account thermal storage of building envelope, explicit expressions have been obtained for room air temperature and room air humidity. For comparing their performance under different climatic conditions, numerical calculations have been made taking meteorological parameters for a typical day for Delhi (composite climate), Jodhpur (hot-dry climate) and Madras (hot-humid climate). It is found that the indirect evaporative cooler is a more effective and energy efficient system than the air-conditioner; it can hence be commercially used for computer and electronic exchange applications as well as for human comfort in a variety of climatic conditions, whereas direct evaporative cooler has limited use (only in hot-dry and composite climates). © 1997 by John Wiley & Sons, Ltd.     

Performance evaluation and comparison of multistage indirect evaporative cooling systems in two operation modes

The evaporative cooling technique is an efficient approach for cooling application. This study aims to establish a performance evaluation method to advance the appropriate design for multistage indirect evaporative cooling systems. A mathematical formulation has been developed for the indirect evaporative cooler (IEC). After the validation, the mathematical model was used to analyze the evaluation criteria by considering the simultaneous influence of the cooling effectiveness, the pressure drop, and the cooling capacity of the multistage IEC operating in two modes. The Mode-1 IEC is a conventional counterflow unit, while the Mode-2 IEC employs a regenerative M-cycle arrangement. The IECs are operated in a tandem arrangement. The multistage system is capable of improving the cooling performance and reducing the outlet air temperature. In addition, the multistage system displays a higher pressure drop resulting in a lager consumption of fan power. The analysis of performance evaluation criteria indicates that the appropriate maximum stage is suggested to be three-stage and two-stage for the Mode-1 and the Mode-2 IEC, respectively.     

蒸发冷却空调地铁站应用的可行性分析

对地铁站的空调通风特点及建筑环境状况进行了分析总结,得出我国现行地铁站空调通风系统耗能大、空气品质不佳等问题,通过对我国现行地铁站空调通风系统的现状与蒸发冷却空调自身特性以及国外此方面实际应用效果的比较得出,若将蒸发冷却这种节能、环保的空调应用于干燥、中湿度地区的地铁站(湿度地区辅助应用),可以较好地解决现行地铁站空调...     

Recent research on an indirect evaporative cooler. Part VI: evolution of design pattern for indirect evaporative cooler

A rule of thumb for indirect evaporative cooler has been derived in terms of the size of floor area to be cooled and design parameters of tube type IEC, viz. process stream air flow rate and number of tubes; the three Indian climate zones, namely hot–dry, composite and warm–humid, represented by three cities of Jodhpur, Delhi and Madras, respectively, have been considered. Copyright © 1999 John Wiley & Sons, Ltd.     

Recent research on an indirect evaporative cooler (IEC) Part 2: thermal performance of a non-conditioned building coupled with an IEC

The thermal performance of a non-conditioned building fitted with an indirect evaporative cooler (IEC) has been investigated in terms of hourly, monthly and seasonal discomfort index. The effect of various design parameters of the IEC on the discomfort index has been investigated for three different climatic areas of India, i.e. hot–dry, warm, humid and composite. The analysis has shown that the IEC is effective for creating thermal comfort conditions in buildings in dry–hot and composite climates. © 1997 by John Wiley & Sons, Ltd.     

Recent researches in indirect evaporative cooler III: optimization of the cooling potential of a room–coupled indirect evaporative cooler

A mathematical model based on heat transfer principles, for characterizing the cooling performance of a room coupled indirect evaporative cooler (tube type) has been developed. Two dimensionless parameters, i.e. environment factor, ϕ and cooling factor, CF have been defined to characterize the performance of IEC coupled with a room. The optimum values of these parameters have been obtained for different environmental and thermal load conditions. In addition to this, a linear relationship has been obtained for the optimum size of a cooler to remove maximum heat from a room of given size. © 1998 John Wiley & Sons, Ltd.     

高湿度地区某整理车间蒸发冷却空调系统设计分析

江阴市某纺织品整理车间设计空调系统,对车间进行降温,改善工人工作环境。针对达到规范所要求的室内温湿度和适当放宽室内温湿度(在人体舒适区域内)时,提出蒸发冷却与机械制冷相结合的空调方案及蒸发冷却空调方案,并根据各自方案的特点、风量及制冷量等情况,得出应用蒸发冷却空调的可行性,最后根据此车间的特点,对方案进行优化,使得蒸发冷却与工位送风相结合,初投资和运行费用更低、节能效果更加显著。     

Cooling energy consumption and operating costs: evaporative all‐air and air‐and‐water systems in the Italian climate

The economic analysis for running two kinds of hybrid air conditioning systems: all‐air and air‐and‐water, both with add‐on evaporative cooling stages, is studied in this paper. Single‐duct, single‐zone, constant volume systems are dealt with. Processing the climatic data of the European ‘test reference year—TRY’ for Italy, a comparison of such systems' performance versus the relative traditional one is performed. Energy consumption and operating costs are evaluated by an appropriate computer code written with the aim of: (i) making plain the input/output of data; and (ii) displaying very friendly software masks as well as useful graphical elaboration. On the basis of outdoor air state, calculations are performed according to two different procedures: (a) hourly, following the TRY profile; and (b) for each bin, 1°C wide, in which the simultaneous dry‐ and wet‐bulb temperatures fall. Copyright © 2000 John Wiley & Sons, Ltd.     

蒸发式冷凝器用于火电厂冷却系统中的可行性分析

概述了火电厂冷却系统的特点，介绍了蒸发式冷凝器的工作原理，基于朗肯循环详细分析了蒸发式冷凝器用在火电厂冷却系统中所具有的优点，从而提出了在我国运用这项技术的必要性，并通过两个实例说明蒸发式冷凝器用于火电厂的冷却系统是可行的。     

Application of passive downdraught evaporative cooling (PDEC) to non-domestic buildings

The applicability of Passive Downdraught Evaporative Cooling (PDEC) for reducing energy consumption in hot dry climates is reviewed. A new EC Joule project explaining the application of PDEC in non-domestic buildings is described. The building performance assessment methodology which employs dynamic thermal simulation programs for thermal analysis, and computational fluid dynamics (CFD) codes for airflow modelling is discussed. The role which wind tunnel tests and field measurements have in producing improved models is noted. Preliminary results from CFD benchmark trials are presented.     

Experimental validation of a thermal model of an evaporative cooling system

A periodic thermal model for an evaporative cooling system over the roof has been presented. Open roof pond, water film and flowing water layer are the the special cases of the analysis. The time dependency of solar radiation, ambient air, sol-air and room air temperatures has explicitly been taken into account by expressing as a Fourier series of time for a 24 h cycle. Experimentally observed air temperature of rooms, treated with and without evaporative cooling over the roof, has been found in good agreement with theoretical results.     

Effect of pre‐cooling of inlet air to condensers of air‐conditioning units

Energy conservation and increase in performance of air‐conditioning systems could be achieved by pre‐cooling the air intake of the condensers. This paper experiments three different methods of pre‐cooling the condenser air; the cooling pad (CP) setup, the cooling mesh (CM) setup and the shading setup. The CP and CM setups are two different methods of evaporatively cooling the air. The three methods have been applied to three identical, 2.8 tons, split air‐conditioning units during the peak summer time period in Kuwait, under ambient temperatures ranging from 39 to 45°C. The results yielded a drop in the power consumption ranging from 8.1 to 20.5% and an increase in the cooling load ranging from 6.4 to 7.8% by using the CP and CM setups, which, in turn, resulted in an increase in the coefficient of performance (COP) of the units by 36–59%. The shading setup has resulted in an increase of power consumption due to air trapped below the shaded area, which resulted in heat being generated. Copyright © 2005 John Wiley & Sons, Ltd.     

用于汽轮机排汽冷却的蒸发式冷凝器模型及性能分析

蒸发式冷凝器兼具传热性能好和节水的优势,在大型动力系统冷却中具有广阔的应用前景。建立了蒸发冷凝器的理论分析模型,提出了蒸发式冷凝器用于冷却小型汽轮机排汽的设计方案;获得了喷淋水温度、空气和蒸汽的焓值在冷凝器内沿程的变化规律,并对喷淋水量、配风量和空气温度等影响冷凝器性能的影响因素进行了分析。研究结果对蒸发式冷凝器在火力发电行业的应用具有参考意义。     

Theoretical and testing performance of an innovative indirect evaporative chiller

An indirect evaporative chiller is a device used to produce chilled water at a temperature between the wet bulb temperature and dew point of the outdoor air, which can be used in building HVAC systems. This article presents a theoretical analysis and practical performance of an innovative indirect evaporative chiller. First, the process of the indirect evaporative chiller is introduced; then, the matching characteristics of the process are presented and analyzed. It can be shown that the process that produces cold water by using dry air is a nearly-reversible process, so the ideal produced chilled water temperature of the indirect evaporative chiller can be set close to the dew point temperature of the chiller’s inlet air. After the indirect evaporative chiller was designed, simulations were done to analyze the output water temperature, the cooling efficiency relative to the inlet dew point temperature, and the COP that the chiller can performance. The first installation of the indirect evaporative chiller of this kind has been run for 5 years in a building in the city of Shihezi. The tested output water temperature of the chiller is around 14–20 °C, which is just in between of the outdoor wet bulb temperature and dew point. The tested COP_r,s of the developed indirect evaporative chiller reaches 9.1. Compared with ordinary air conditioning systems, the indirect evaporative chiller can save more than 40% in energy consumption due to the fact that the only energy consumed is from pumps and fans. An added bonus is that the indirect evaporative chiller uses no CFCs that pollute to the aerosphere. The tested internal parameters, such as the water–air flow rate ratio and heat transfer area for each heat transfer process inside the chiller, were analyzed and compared with designed values. The tested indoor air conditions, with a room temperature of 23–27 °C and relative humidity of 50–70%, proved that the developed practical indirect evaporative chiller successfully satisfy the indoor air conditioning load for the demo building. The indirect evaporative chiller has a potentially wide application in dry regions, especially for large scale commercial buildings. Finally, this paper presented the geographic regions suitable for the technology worldwide.     

Recent research on an indirect evaporative cooler (IEC) Part 1: optimization of the COP

The paper presents an analysis for optimizing the coefficient of performance of an tube type indirect evaporative cooler (IEC) in terms of process stream air velocity and wet stream air velocity. Theoretical predictions of the optimum COP value have been compared with the experimental results obtained for an IEC at Indore in the summer months of May and June; the agreement is satisfactory. © 1997 John Wiley & Sons, Ltd.     

Thermoeconomic optimization of an ice thermal storage system for gas turbine inlet cooling

The gas turbine power output and efficiency decrease with increasing ambient temperature. With compressor inlet air cooling, the air density and mass flow rate as well as the gas turbine net power output increase. The inlet cooling techniques include vapor or absorption refrigeration systems, evaporative cooling systems and thermal energy storage (TES) systems. In this paper the thermoeconomic analysis of ice (latent) thermal energy storage system for gas turbine inlet cooling application was performed. The optimum values of system design parameters were obtained using genetic algorithm optimization technique. The objective function included the capital and operational costs of the gas turbine, vapor compression refrigeration system, without (objective function I) and with (objective function II) corresponding cost due to the system exergy destruction. For gas turbines with net power output in the range of 25-100 MW, the inlet air cooling using a TES system increased the power output in the range of 3.9-25.7%, increased the efficiency in the range 2.1-5.2%, while increased the payback period from about 4 to 7.7 years.