扩散及吸附剂特性系数对转轮除湿器性能的影响

将转轮除湿器数学模型无量纲化，得到影响除湿器性能的无量纲扩散特性和吸附剂特性系数。通过数值计算，对这些系数影响除湿器性能的变化趋势作了讨论，阐明周向及轴向热扩散和质扩散的影响，从而更全面地揭示转轮除湿器的工作本质。     

转轮式干燥剂除湿器性能的相似分析与计算

对转轮式除湿器的控制方程及其边界条件和吸附剂的物性方程进行了相似分析，得到了影响除湿性能的１２个参数（１０个无量纲参数和２个有量纲参数）。在运行参数一定的条件下，转轮除湿器性能是其中７个无量纲参数的函数。阐述了７个无量纲参数的物理意义并通过数值模拟得到了它们对除湿性能的影响规律，为转轮式干燥剂除湿器的优化设计奠定了基础。     

转式干燥剂除湿器性能的相似分析与计算

对转轮式除湿器的控制方程及其边界条件和吸附剂的物性方程进行了相似分析，得到了影响除湿性能的１２个参数（１０个无量纲参数和２个有量纲参数）。在运行参数一定的条件下，转除湿器性能是其中７个无量纲参数的函数。阐述了７个无量纲参数的物理意义并通过数值模拟得到了它们对除湿性能的影响规律，为转轮式干燥剂除湿器的优化设计奠定的基础。     

带冷却液体除湿系统性能分析的简化方法

采用无量纲蒸汽压差值比和温度差值比对液体除湿系统进行研究,对带冷却液体除湿系统的简化模型进行了计算,并与一组实验数据做了对比,取得了较为满意的效果。分析结果表明用此方法来计算除湿器中除湿量是可行的,且简便易行。该文同时研究了溶液流量、溶液入口温度、浓度等因素对带冷却液体除湿器性能的影响。     

液体除湿系统的研究发展

液体除湿空调不仅可以对热负荷和湿负荷独立处理,而且不断循环的盐溶液还可以对空气起到很好的杀菌效果,这可以提高人们生活和工作的空气品质,避免由传统空调引起的温室效应。但是在溶液除湿和再生的过程中溶液表面的水蒸气压力与空气的水蒸气压力差不断减小,阻碍了除湿过程和再生过程的进行,所以为了得到更高的效率,需要探索新型的液体除湿装置。液体除湿系统主要由除湿器、再生器、循环溶液组成,其中再生器的性能直接影响到整个液体除湿系统的性能。简要介绍了传统液体除湿系统的再生器、除湿器、除湿溶液及新型液体除湿系统再生器的发展。     

太阳能液体除湿空调系统中除湿器型式的选择

太阳能液体除湿空调系统是一种利用太阳能等低温热源的节能空调系统。除湿器直接影响太阳能液体除湿空调系统的性能。本文从焓湿图、蓄能、MR的选取和除湿效果等几个方面对目前被广泛应用的两种典型的除湿器进行了比较分析。     

太阳能再生式除湿换热器动态除湿性能研究

提出了一种新型再生式除湿换热器,建立了物理和数学模型。通过实验得到了该除湿换热器的实际动态除湿性能;将除湿器除湿性能的模拟结果与实验结果进行比较,验证了数学模型的可靠性。研究结果表明:该文研制的再生式除湿换热器具有良好的除湿性能,在给定工况(温度为24.7℃,含湿量为12.41g/kg)下除湿率可达到43.8%;还分析了处理风速、再生温度以及除湿换热器厚度对除湿性能和压降的影响,获得了使除湿换热器性能最佳的管排、翅片间距和迎面风速参数。     

内冷却紧凑式叉流除湿器性能数值模拟与分析

该文提出了一种内冷却紧凑式叉流除湿器，对的该除湿器的除湿以及再生过程建立了热质交换的二维动态数学模型，并运用全隐式差分格式获得了该模型的数值解，对影响该类除湿器工作性能的多种因素及其作用结果进行了分析和对比，为除湿器结构的设计、工作状态点的选择提供了必要的理论依据。结果表明，本文提出的内冷却紧凑式叉流除湿器的性能较普通固定床式除湿器的性能有显著提高。     

内冷型液体除湿器数学模型及性能分析

提出了一种内冷型液体除湿器,并对该除湿器的除湿过程建立了热质交换的稳态数学模型.通过与实验结果的比较,发现数值计算结果与实验结果吻合较好,多数数据的偏差都在±10%以内.分析了各参数对除湿性能的影响,为除湿器的结构设计和性能分析提供了理论和应用依据.     

蓄能型液体除湿蒸发冷却系统中除湿性能的实验研究

提出了一种新型空调系统——液体除湿冷却空调系统的设计方案并搭建一功率为3kW的实验台，考虑到除湿过程和再生过程是该系统性能优良的决定性环节，设计加工了水冷型波纹板降膜式结构的除湿器和以丝网填料作为内部填料的再生器。在此实验装置上对系统的除湿过程以及其蓄能能力特性进行了实验研究，得出影响该系统除湿能力、蓄能能力等方面的主要因素，为系统的优化设计和运行提供依据。     

Evaluation and optimization of solar desiccant wheel performance

This paper presents the evaluation and optimization of a solar desiccant wheel performance. A numerical model is developed to study and discuss the effect of the design parameters such as wheel thickness, wheel speed, regeneration to adsorption area ratio, wheel porosity, and the operating parameters such as air flow rate, inlet humidity ratio of the air and regeneration air temperature on the wheel performance. It is also used to draw the performance curves of the desiccant wheel to quantify the optimum design parameters for certain operating conditions.Also, an open test loop for the desiccant wheel is constructed with appropriate control devices and measuring instruments. A perforated plate solar air heater of 2 m² area, together with an electric heater, is used as a source of energy to regenerate the desiccant material. The experimental tests are used to validate the numerical model and to evaluate the performance of the solar system and the desiccant wheel under actual conditions of Cairo climate (30° latitude).Comparison between numerical and experimental results shows good agreement between them, especially at low flow rates of air. Numerical results show that there is a maximum value of each design parameter at each operating condition, and above that no remarkable changes in the wheel performance are noticed. The results also show that there is an effective range of the air flow rate, due to which wheel performance becomes inefficient. This range is found to be between 1 and 5 kg/min. The performance curves of the wheel, which help to determine the humidity reduction ratio, are drawn for wheel speeds between 15 and 120 rev/h, dimensionless wheel thickness between 0.15 and 0.5, air flow rate equal to 1.9 and 4.9 kg/min, and regeneration temperature equal to 60 and 90 °C. These curves show that there is an optimum value of the wheel speed for each wheel thickness to obtain the best wheel performance for certain operating conditions.Experimental results show that the perforated plate solar air heater of 2 m² area can share about 72.8% of the total regeneration energy required at 1.9 kg/min air flow rate and 60 °C the regeneration air temperature. This value decreases to about 13.7% at a flow rate equal to 9.4 kg/min and regeneration temperature equal to 90 °C. The perforated plate solar air heater area required to completely fulfill the regeneration energy during the daytime is also calculated.     

Parametric analysis of desiccant wheel for air conditioning application

A one‐dimensional mathematical model is developed to evaluate the operating and design parameters of the desiccant wheel for air conditioning application. In this paper, dehumidification coefficient of performance (DCOP) and sensible energy ratio (SER) are adopted as a combined performance index to reflect the dehumidification and thermal performance of the desiccant wheel. The analysis of the results reveals that for lower SER, suitable wheel length, wall thickness, channel pitch, and channel height should be 100 mm, 0.2 mm, 3 mm, and 5 mm, respectively. These design parameters have been analyzed under different operating conditions and it was found that for higher DCOP, rotational speed, regeneration temperature, process and regeneration velocity should be 20 rph, 60°C, and 2 m/s.     

Performance analysis of induced draft cooling tower integrated with rotary silica gel mesh

A humid environment decreases the performance of induced draft counter flow cooling towers (IDCFCT) normally used in power plants and process industries. The primary objective of this study is to experimentally analyze the effect of using rotary silica gel mesh (RSGM) on the performance of IDCFCT. Experimental setups of IDCFCT with and without RSGM have been designed and fabricated to perform the comparative analysis. The performance of both cooling towers (CTs) in terms of output temperature, relative humidity of air, range, approach, and effectiveness at different air velocities has been investigated. The results indicate that the outlet air temperature of IDCFCT integrated with the RSGM wheel is 0.5–1.5°C higher than the IDCFCT without the RSGM wheel. IDCFCT with RSGM wheel shows maximum effectiveness of 0.67 at an air velocity of 1.5 m/s and inlet water temperature of 55°C; whereas, for IDCFCT without RSGM wheel, it is only 0.54. In terms of efficiency, RSGM wheel integrated IDCFCT shows an improvement of 24% compared to IDCFCT without RSGM wheel. It has been observed that RSGM-integrated IDCFCT also helps to save water up to 431.7 kg/h at an air velocity of 1 m/s with a water inlet temperature of 35°C. Moreover, the advantage of integrating the RSGM wheel with IDCFCT has been further corroborated in terms of the reduction in the height of the CT obtained with the help of a thermodynamic model.     

Modeling analysis of an enthalpy recovery wheel with purge air

A purge section is typically used to reduce the carryover of contaminants in enthalpy recovery wheels. A one-dimensional transient heat and mass transfer model is developed to analyze the performance of enthalpy recovery wheels both with and without purge air. The governing equations are coupled, and the variables are solved using a trial and error method. The enthalpy recovery wheel model without purge air is validated using previously published results with good agreement. Finally, the results of an enthalpy recovery wheel with purge air are presented, and indicate that there is an optimum wheel depth and rotation speed to achieve maximum performance for enthalpy recovery wheels with purge air.     

Practical thermal performance correlations for molecular sieve and silica gel loaded enthalpy wheels

The central thrust of this research was to develop practical enthalpy wheel effectiveness correlations useful for enthalpy wheel integrated systems design and analysis. In this research, enthalpy wheel performance data generated using established fundamental enthalpy wheel models were statistically analyzed. And then, first order linear regression equations were derived to estimate the enthalpy wheel sensible and latent effectiveness at normal operating rotational speeds (i.e. over 20 rpm). The two most common desiccant materials, silica gel and molecular sieve on aluminum substrate, were analyzed. Each correlation relates the enthalpy wheel sensible and latent effectiveness as a function of six parameters; incoming outdoor air and exhaust air temperature and relative humidity, face velocity, and air flow ratio. The enthalpy wheel leaving air conditions can then be simply estimated by employing the practical effectiveness correlations. Predicted effectiveness values corresponded well with published manufacturer’s data and existing fundamental enthalpy wheel models.     

装载机载荷谱分析及应用

介绍装裁机载荷谱数据的分析方法,并用两种不同方法相互论证数据分析的准确性。通过两种不同发动机的数据比较,对装载机用发动机的性能开发具有一定的指导作用。     

Comparative Performance of Different Sector Arrangement in a Desiccant Wheel Using a Mathematical Model

A one‐dimensional mathematical model has been used for a three‐sector desiccant wheel (two sectors with purge) with different flow arrangements. The model considers both gas and solid side resistance and shows a good agreement with experimental results. This model has been used to conduct a comparative performance analysis in both the effective adsorption and effective regeneration sector of a desiccant wheel. It was found that an effective regeneration sector gives better results for the performance parameters (rotation of wheel, regeneration temperature, velocity, and ambient moisture) as compared to an effective adsorption sector. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21103     

轮轨非对称接触及形面损伤问题分析

随着列车运行速度的提高,车轮形面损伤问题也日益严重。车轮形面损伤分为踏面剥离、车轮失圆和轮缘磨耗等类型。车轮形面损伤后会导致车辆的不平稳运行,使车辆一方面产生低频、中频和高频的振动,影响车辆的运行平稳性和乘坐舒适性,另一方面会引起车辆内部的噪声,车轮损伤严重时甚至会直接导致车辆脱轨事故的发生。车轮损伤问题是由轮轨接触非对称现象所引起的,轮轨非对称接触分为对称踏面与非对称钢轨的接触、非对称踏面与对称钢轨的接触以及非对称踏面与非对称钢轨的接触三种类型。当车轮形面或钢轨损伤后,就会导致轮轨非对称接触的发生,而轮轨非对称接触又会加剧车轮形面的损伤。为了提高车辆的动力学性能和运行稳定性,必须避免轮轨强非对称接触的发生。     

Optimization of desiccant wheel speed and area ratio of regeneration to dehumidification as a function of regeneration temperature

Numerical simulation has been conducted for the desiccant wheel, which is the crucial component of a desiccant cooling system. The mathematical model has been validated by comparing with previous experimental data and numerical results. The calculation results are in reasonable agreement with both, experimental and numerical results. As the key operating/design parameters, the wheel speed and the area ratio of regeneration to dehumidification have been examined for a range of regeneration temperatures from 60 °C to 150 °C. Optimization of these parameters is conducted based on the wheel performance evaluated by means of its moisture removal capacity (MRC) which is more appropriate than effectiveness as a performance index of unbalanced flows. Also the effects of the outdoor air temperature and humidity on the optimum design parameters are examined.     

Thermal models of railroad wheels and bearings

The rolling surface for railroad wheels can be a heat source that may have an impact on the performance of the wheel bearing. In this study, experimental data from an electrically-heated railroad wheel set is analyzed by constructing thermal models of the wheel set. A steady finite-element model, a steady-analytical model, and a transient lumped-parameter model are discussed. Model parameters are determined from careful comparisons with the experimental data. The lumped-parameter model given here is intended as a simple predictive tool for determining when wheel heating caused by rail operations will have an impact on bearing temperature. The model parameters found in this study will also be useful as experimentally-validated boundary conditions in ongoing finite-element studies of heated wheels.