气体水合物蓄冷技术

通过对气体水合物蓄冷技术基本原理的描述，概括总结了迄今为止对氟里昂气体水合物蓄冷的研究现状和发展概况，揭示在实用空调蓄冷系统中气体水合物作为新的蓄冷技术的节能优势，指明了气体水合物蓄冷技术应用于空调系统中仍需解决或需引起注意的问题。     

蓄冷球内高温相变材料蓄冷特性的研究

针对一种自行开发具有较高融点的新型高温相变材料进行了蓄冷特性的理论与实验研究,得到了在不同工况下蓄冷量和球内相界面位置随时间的变化关系。结果表明实验数据与理论计算基本相符,并分析了实验数据与理论数据之间存在的误差原因。所得到的结论对蓄冷装置的节能设计和工程应用具有一定的参考价值。     

相变蓄冷装置内传热及相变特性研究

建立了三种不同蓄冷球球径堆叠方式的相变蓄冷装置模型,对其进行了数值模拟以研究其内部传热及相变特性。结果表明：随着流速的提高、蓄冷球直径的减小,蓄冷结束后三种方案中装置内蓄冷球的凝固率提升显著;双球径方案与单球径方案装置内蓄冷球凝固率随时间变化的规律在蓄冷过程初段相类似,但两方案中相同球径部分蓄冷球相变结束,双球径方案中发生相变的蓄冷球由大直径转变为小直径时,其凝固率随时间变化的速度逐渐超过单球径方案。该研究可为相变蓄冷装置的实际设计及性能优化提供参考     

相变蓄冷原理及其应用

冷量储存是工业生产和日常生活中许多地方需要用到的一种能量储存形式，也是一种节能的重要方式。目前，工业生产中冷量的储存和运用大多是采用显热原理，而采用相变潜热原理进行冷量的储存和运用，近几年来国外、国内都开始了研究和应用。本文在阐述了相变蓄冷原理之后，对相变蓄冷介质、相变蓄冷设备及其应用进行了较深入的探讨。相信，本文对利用相变蓄冷原理进行冷量储存和节能工作的发展，会有一定裨益的。     

数据中心蓄冷系统的选择及蓄冷时间的确定

通过对蓄冷介质、蓄冷形式的分析,结合数据中心的具体情况,考虑保障其充放冷过程可靠运行,对一次泵与二次泵系统、蓄冷罐并联串联的优劣进行比较,最终得出数据中心使用蓄冷罐的原因,所使用蓄冷罐的介质形式,所使用蓄冷罐的连接形式,以及空调系统形式与蓄冷罐连接形式的关系,为蓄冷罐的选择及蓄冷罐形式与制冷系统形式的匹配提供参考。确定蓄冷系统的形式之后,还要确定蓄冷量的大小,以确定蓄冷时间,蓄冷时间关系到整个数据机房的安全可靠性,而蓄冷量的大小则对节能和建筑空间利用率有较大影响。通过对市电直至冷机满负荷运行过程的各个环节进行分解,从安全可靠性最小保障时间角度进行核实,最终确定蓄冷系统的最小需要时间。     

小型蓄冷空调系统的实验研究

本文描述了一套小型蓄冷调控系统,并采用有机相变材料进行了性能实验,得到了系统各参数随时间的变化规律;在此分析基础上,对小型蓄冷空调系统的设计提出了建议。     

蓄冷成功应用的实例研究

1、问题的提出 位于加利福尼业州波威市的一家医院准备扩建42％,按照原设计,需增加一台320吨的制冷机、一座冷却塔和一台表压为0.45Mpa(65psig)的蒸汽锅炉。但是医院希望在不增加这套设备的情况下完成扩建,这是可能实现的。因为设备部门曾经实施过一些行之有效的节能项目,而且考虑过热能蓄存可能带来的好处。如果能证明安装一套蓄冷系统在经济上是可行的,这套系统将在医院扩建前或扩建的同时完成。     

直接蓄冰系统蓄冷过程动态模型研究

分析了直接蓄冰系统的动态特性,建立了相应的物理模型,并利用该模型得出了蓄冰半径及蓄冷率随时间的变化规律,模型预测值与实测值吻合较好。该模型可为直接蓄冰系统的设计及优化提供理论依据。     

蓄冷成功应用的实例研究

1、问题的提出位于加利福尼亚州波威市的一家医院准备扩建42％,按照原设计,需增加一台320吨的制冷机、一座冷却塔和一台表压为0.45MPa(65psig)蒸汽锅炉。但是医院希望在不增加这套设备的情况下完成扩建,这是可能实现的。因为设备部门曾实施过一些行之有效的节能项目,而且考虑过热能蓄存可能带来的好处。如果能证明安装一套蓄冷系统在经济上可行的,这套系统将在医院扩建     

空调蓄冷材料及蓄冷球内非固定融化问题的研究

通过实验方法研究了空调蓄冷材料的相变温度、相变潜热和比热等热学性能。并对该种蓄冷材料制成的蓄冷球进行了释冷特性的研究,探讨了蓄冷球内固液密度差引起的固态物上浮对蓄冷球融化释冷的影响,得到了融化率随时间的变化关系。结果表明:该蓄冷材料融解热为149.4kJ/kg,相变温度为7.9℃,该相变材料可作为空调蓄冷材料,蓄冷球的直径及固液密度差对融化释冷特性有较大影响。     

Experimental study on a small scale of gas hydrate cold storage apparatus

To have an overall investigation of cold storage characteristics to help to promote the application, a novel small scale of gas hydrate cold storage apparatus was designed. The amount of cold energy, growth rate, Hydrate Packed Factor (HPF) and overall heat transfer coefficient during the cold storage process were calculated and analyzed under different heat exchangers, sodium dodecyl benzene sulfonate (SDS) concentrations, hydration enhancement ways, inlet coolant temperatures and flow rates, etc. Results show that the cold storage performance could be improved greatly by adding a heat exchanger with vertical metal fins; SDS with concentration of 0.04 wt.% could help to improve the cold storage performance effectively. In addition, decreasing of the coolant temperature or increasing of the coolant flow rate could also make the amount of cold storage increased; it was found that mechanical blending for 5 min was the better hydration enhancement way than others, which presents the perspective for practical application.     

Experimental investigation of effect of ventilation strategies on the performance of cold storage

Fresh fruits and vegetables are living organisms that require fresh air to survive while being stored. Respiratory gases can build up and damage produce if there is not enough ventilation during storage. Ventilation is required to prevent an excessive build-up of respiratory gases and to maintain the freshness of produce. In hot and dry areas, air ventilation of refrigerated storage can have a negative impact on food produce quality and affect storage performance. An indoor experimental study was carried out to investigate the air ventilation of the cold room during various modes of air supply. The energy recovery device (ERD) with and without evaporative cooling arrangement is used in the air supply and the performance enhancement is compared. The ERD reduces the air ventilation load by more than 50% compared to direct ventilation of the cold room and consequently, it reduces the total power consumption of air ventilation. Furthermore, the overall cooling performance of the system is improved by up to 45.7% when the ERDs are used compared to the direct supply of fresh air during air change mode and the use of energy-saving equipment has also proven improvements in the desired air conditions for food production.     

Experimental investigation of hydrogen storage in capillary arrays

We present the results of the experimental investigation of hydrogen storage in glass capillary arrays. It is demonstrated that quartz–epoxy capillary arrays can have extremely high gravimetric and volumetric capacity, exceeding US DOE 2010 target values. The new method of pressurized hydrogen loading and releasing is developed based on plugging up the capillaries with stoppers in high-pressure environment.     

Experimental investigation of an adsorptive thermal energy storage

A zeolite‐water adsorption module, which has been originally constructed for an adsorption heat pump, has been experimentally investigated as an adsorptive thermal energy storage unit. The adsorber/desorber heat exchanger contains 13.2 kg of zeolite 13X and is connected to an evaporator/condenser heat exchanger via a butterfly valve. The flow rate of the heat transfer fluid in the adsorber/desorber unit has been changed between 0.5 and 2.0 l min^?1, the inlet temperature to the evaporator between 10 and 40°C. It turned out that the higher the flow rate inside the adsorber/desorber unit the faster and more effective is the discharge of heat. However, at lower flow rates higher discharge temperatures are obtained. Storage capacities of 2.7 and 3.1 kWh have been measured at the evaporator inlet temperatures of 10 and 40°C, respectively, corresponding to thermal energy storage densities of 80 and 92 kWh m^?3 based on the volume of the adsorber unit. The measured maximum power density increases from 144 to 165 kWh m^?3 as the flow rate in the adsorber increases from 0.5 to 2 l min^?1. An internal insulation in form of a radiation shield around the adsorber heat exchanger is recommended to reduce the thermal losses of the adsorptive storage. Copyright © 2006 John Wiley & Sons, Ltd.     

Experimental investigation of a molten salt thermocline storage tank

Thermal energy storage is considered as an important subsystem for solar thermal power stations. Investigations into thermocline storage tanks have mainly focused on numerical simulations because conducting high-temperature experiments is difficult. In this paper, an experimental study of the heat transfer characteristics of a molten salt thermocline storage tank was conducted by using high-temperature molten salt as the heat transfer fluid and ceramic particle as the filler material. This experimental study can verify the effectiveness of numerical simulation results and provide reference for engineering design. Temperature distribution and thermal storage capacity during the charging process were obtained. A temperature gradient was observed during the charging process. The temperature change tendency showed that thermocline thickness increased continuously with charging time. The slope of the thermal storage capacity decreased gradually with the increase in time. The low-cost filler material can replace the expensive molten salt to achieve thermal storage purposes and help to maintain the ideal gravity flow or piston flow of molten salt fluid.     

Modeling of CO2 storage as hydrate in vacated natural gas hydrate formation

Holding CO₂ at massive scale in enclathrated solid matter called hydrate can be perceived as one of the most reliable method for CO₂ storage in subsurface geological environment. In this study, a dynamically coupled mass, momentum, and heat transfer mathematical model is developed, which elaborates uneven behavior of CO₂ flowing into porous medium in space and time domain and converting itself into hydrates. The combined numerical model solution methodology by explicit finite difference iteration method is provided and through coupling the mass, momentum, and heat conservation relations, an integrated model can be presented to investigate the CO₂ hydrate growth within P-T equilibrium conditions. The article results illustrate that pressure distribution in hydrate formation becomes stable at initial phase of hydrate nucleation process, but formation temperature is unable to maintain its stability and varies during CO₂ injection and hydrate nucleation process. The hydrate growth rate increases by increasing injection pressure from 15 MPa to 16 and 17 MPa in 500-m-long formation, and it also expands overall hydrate-covered length from 200 m to 280 m and 320 m, respectively, in 1 month of hydrate growth period. Injection pressure conditions and hydrate growth rate affect other parameters like CO₂ velocity, CO₂ permeability, CO₂ density, and CO₂ and H₂O saturation. In order to enhance hydrate growth rate and expand hydrate-covered length, injection temperature is reduced from 282 K to 280 K, but it did not give satisfactory outcomes. In addition, hydrate growth termination and restoration effect is also witnessed due to temperature variations.     

Experimental and numerical investigation of thermal energy storage with a finned tube

A latent heat thermal energy storage system using a phase change material (PCM) is an efficient way of storing or releasing a large amount of heat during melting or solidification. It has been determined that the shell‐and‐tube type heat exchanger is the most promising device as a latent heat system that requires high efficiency for a minimum volume. In this type of heat exchanger, the PCM fills the annular shell space around the finned tube while the heat transfer fluid flows within the tube. One of the methods used for increasing the rate of energy storage is to increase the heat transfer surface area by employing finned surfaces. In this study, energy storage by phase change around a radially finned tube is investigated numerically and experimentally. The solution of the system consists of the solving governing equations for the heat transfer fluid (HTF), pipe wall and phase change material. Numerical simulations are performed to investigate the effect of several fin parameters (fin spacing and fin diameter) and flow parameter (Re number and inlet temperature of HTF) and compare with experimental results. The effect of each variable on energy storage and amount of solidification are presented graphically. Copyright © 2005 John Wiley & Sons, Ltd.     

冷库现状及冷库节能途径

论述了当前我国冷库行业的发展现状,指出了我国冷库设计、建设和管理等方面存在的问题,并给出了一些节能的方法。     

Thermal conductivity of metal hydride materials for storage of hydrogen: Experimental investigation

The effective thermal conductivity of a powdery material, comprising heat conduction in the solid particles and in gas and temperature radiation across the pores, was determined by the transient hot wire method. The materials investigated were LaNi_4.7Al_0.3H_x, which is practically applied at medium temperature, and HWT 5800, applied at low temperatures. The temperature range investigated was −80 to +140 °C, the pressure range 10⁻⁶ to 60 bar. The porosity of the powder material in the state of delivery was 0.045 and 0.531. Concentration/pressure isotherms (CPI) and the effective thermal conductivity k_eff were measured. Various filling gases (H₂, He, N₂, Ar) were used. There is a clear effect of the gas in the state of delivery of the powder. An effect of particle decay can be observed. The effective thermal conductivity depends primarily on the hydrogen pressure, while the temperature has only an indirect influence.