新风量、送风方式和空调病症

本文叙述了新风量的大小和送风方式的不同与空调病症之间的关系。     

新风量、送风方式和空调病症

本文叙述了新风量的大小和送风方式的不同与空调病症之间的关系。     

对全空气定风量系统“可调新风比”的探讨与建议

<正>在公共建筑的空调设计中,常用的空调形式为全空气系统、风机盘管+新风系统、温湿度独立控制系统。无论采用哪种空调系统,都要根据建筑内的人员密度以及空调房间内的人数,确定空调房间的新风量。对于风机盘管+新风系统、温湿度独立控制系统,新风系统完全可以根据计算的新风量设计,相应的每层的新风机房、新风竖井、排风竖井、集中的新风热回收机组都按此新风量进行设计。那么对于全空气系统,又是如何规定的呢?1相关规范对伞空气定风培系统的可调新风比要求     

下送风空调技术综述

随着越来越多现代化、智能化的办公大楼的建设，新型办公楼室内布局的不断变化，以及人们对舒适性尤其是室内空气品质要求的提高，下送风空调方式逐渐被采用。本文介绍了下送风空调技术目前的研究现状，并从这种空调方式的原理出发，综述了下送风技术在热环境、舒适性、空气品质、节能等方面的特点，比较了该系统与传统上送风空调系统之间的差异。最后指出了目前该空调技术在实际应用中的若干问题。     

基于热湿分区的全空气空调系统变新风量节能分析

现代公共建筑的大量增加和全空气空调系统的普遍应用,促使公共建筑能耗大幅增加。基于变风量运行的原理,首先对空气状态进行分区,然后对各区进行详细的运行策略分析。建立了一个定风量系统的房间模型,计算其全年逐时负荷,从而确定送风状态点的全年变化趋势。基于Open-Studio软件,模拟分析4月中上旬至6月上旬、10月下旬至11月上旬是新风量利用潜力最高的时段,且在1月初至7月中旬、11月上旬至12月末时加湿量都明显降低。当新风比可调时,全年的湿负荷、热负荷、冷负荷均减少59.05%、35.54%和12.12%,全空气空调系统在变新风比运行时节能效果十分明显。     

夏季自然通风教室室内环境与学习效率的调查研究

通过环境参数测量与问卷调查结合的方式探索夏季教室室内环境与学生学习效率间的关系。主要分析同济大学两种典型教室正常上课期间室内热环境、空气品质和光环境状况,结果表明教室室内环境存在的主要问题是新风量不足,二氧化碳浓度长期维持在较高的水平,从而导致室内人员学习效率不高。     

能量回收换气机的节能特性研究

本文阐述了空调新风与空气品质之间的关系,对几种通风方式作了对比分析,介绍了能量回收换气机的工作原理和特点,主要对能量回收换气机的节能性进行了计算分析,从而得到能量回收换气机应用的可行性,并对未来能量回收换气技术进行了肯定.     

保证室内空气品质的置换通风的节能研究

介绍了置换通风的原理及其能够改善室内空气品质的原因,运用送风量及送风温度的公式,对置换通风及混合通风进行了计算比较。通过具体工程实例的计算表明:置换通风其送风量比混合通风的送风量减少16.7%,节约能耗41%,新风节能2.46W,是一种能改善室内空气品质的节能方法。     

渗透型太阳能空气集热器集热效率研究

将CFD模拟引入太阳能空气集热器设计研究领域,对渗透型太阳能空气集热器(UTC)的工作特性进行了模拟分析,并与传统空气集热器进行了比较.在数值模拟的基础上,制作了几种实验模型并进行了实验研究,对其送风温度和热效率进行了测试.通过模拟和模型实验,说明了UFC在新风预热领域中无可比拟的优势,显示了CFD工具在空气集热器研究领域中的优势.     

空调房间气流组织的数值模拟研究

利用Fluent软件,从室内的速度场、温度场及室内CO_2浓度场分布出发,模拟研究了某一空调房间内置换通风和侧送风两种空调方式的差异性。结果表明:置换通风方式在提高人体热舒适性、改善工作区空气品质及节能等方面要优于侧送风方式。     

Control performance of a dedicated outdoor air system adopting liquid desiccant dehumidification

Liquid desiccant is energy efficient for dehumidification in air-conditioning systems. In this study, a novel dedicated outdoor air system (DOAS) adopting lithium chloride solution as liquid desiccant is proposed to process supply air. The DOAS mainly consists of a membrane-based total heat exchanger, a liquid dehumidifier, a regenerator and a dry cooling coil. It can realize independent temperature and humidity controls for supply air. Control strategies for the supply air dehumidification and cooling process as well as the desiccant solution regeneration process in the DOAS are developed and verified. The control performances of the proposed dedicated outdoor air system are investigated at different operation conditions by simulation tests. The results show that the DOAS is more suitable for hot and humid climates. The effects of the total heat exchanger on the performance of the DOAS are also evaluated. It can improve the system energy performance by 19.9–34.8%.     

Model-based optimal control of a dedicated outdoor air-chilled ceiling system using liquid desiccant and membrane-based total heat recovery

This study presents a model-based control strategy for a novel dedicated outdoor air-chilled ceiling (DOAS-CC) system with the aim of optimizing the overall system performance. The DOAS-CC system incorporates liquid desiccant dehumidification and membrane-based total heat recovery technologies. Simplified but reliable models of major components in the DOAS-CC system are firstly developed to predict the system performance. A cost function is then constructed to minimize total energy consumption while properly maintaining thermal comfort reflected by indoor air temperature and relative humidity. Genetic algorithm is used to search for optimal set-points of the supply air temperature and humidity ratio of the dedicated outdoor air subsystem as well as the supply water temperature. The performance of this strategy is tested and evaluated with different control settings in a simulated multi-zone space served by the DOAS-CC system under various weather conditions. The results show that optimized control variables produced by the optimal strategy can improve the system energy performance and maintain indoor thermal comfort.     

Energy consumption analysis on a dedicated outdoor air system with rotary desiccant wheel

A dedicated outdoor air system (DOAS) with rotary desiccant wheel is the combination of a desiccant dehumidification system and a vapor compression refrigeration system. An energy consumption model of this hybrid DOAS is established for its analysis. Coefficient of performance, COP, is appropriately defined for evaluation on performance of the hybrid DOAS. The results indicate that, compared with a conventional DOAS, energy savings are possible for the suggested DOAS, when solar energy or natural gas is used for regeneration. Ventilation air flow rate, temperature or humidity of outdoor air, as well as regeneration-to-process air ratio, influence the energy consumption and the COP of the hybrid DOAS, greatly.     

Experimental study on the performance of air source heat pump system with multiple parallel outdoor units

This paper presents a novel air source heat pump for heating of buildings named air source heat pump with multiple parallel outdoor units (ASHPMO). Multiple outdoor units were connected in parallel with the aim of realising alternate defrosting and uninterrupted heating simultaneously. An experimental apparatus of the ASHPMO system was developed. The defrosting performance was experimentally investigated under different outdoor air temperatures, outdoor air relative humidity, and condensation temperatures, among other factors. The test results showed that the novel ASHPMO system could provide continuous heating when defrosting even under an outdoor air temperature of −10°C. Variations in compressor vapour suction and discharge pressure and temperature were observed. The minimum heating capacity could still reach 60% of that without defrosting. Under the defrosting condition with outdoor air temperature −10°C, both the heating coefficient of performance (heating COP) and total energy efficiency ratio (EER) of the system can reach to 2.0 and 2.32, respectively.     

大空间两种气流组织夏季热环境及其能耗实验研究

以某大空间实验基地为研究对象,针对喷口送风和柱状下送风两种分层空调的热环境及供冷量进行了实测研究.研究结果表明:因喷口送风空调区较大,在夏季室外气象参数基本相同的两种室外气象条件下,喷口送风空调系统供冷量比柱状下送风空调系统的供冷量分别高出20.8%、24.4%,且喷口送风空调系统抗干扰能力较柱状下送风强;喷口送风时工作区温度均匀性好于柱状下送风,头足温差较小,但其工作区风速超过标准,而柱状下送风时工作区风速则符合环境设计要求;两种不同送风量下喷口送风时吹风感指数分别为15.64%、11.23%,而柱状下送风时吹风感指数分别为4.17%、2.40%,柱状下送风要明显优于喷口送风.故从节能及热舒适性角度综合考虑,单侧回风的大空间建筑应尽可能采用柱状下送风分层空调,而对于干扰比较大,空调场地较小,无法布置柱状下送风口的场合,则选取喷口送风较好.     

锅炉二次风系统协调控制的研究

采用机理分析和统计分析的方法,建立了二次风系统非线性动态模型,并通过仿真验证了模型的有效性和准确性.该模型分析了目前存在的两种二次风控制系统的优缺点,发现了影响控制品质的主要因素是系统的相互关联,二次风控制的主要矛盾是风量的响应速度和风压的波动.为解决这一矛盾,设计了二次风协调控制系统,优化了动态控制品质.     

Influence of air supply on the performance and internal flow characteristics of a cross flow turbine

This study attempts to improve the efficiency of a given type of cross flow turbine by supplying air from air suction holes. A newly developed air supply method is adopted. CFD analysis of the cross flow turbine is carried out to investigate the performance and internal flow characteristics of the turbine in detail. The air layer prevents shock loss between water flow and axis and suppresses recirculation flow in the runner passage. Hence, it is necessary to measure the amount of air layer in the runner passage and examine its effect on the performance of the cross flow turbine. The result shows that the turbine efficiency has improved more as the newly developed air supply method is applied effectively.     

城市住宅小区建筑室内外环境对局部气候的影响

以天津某高层住宅小区为对象,建立了小区建筑和室内户型的计算分析模型。基于CFD方法,开展了在冬、夏季典型气候下的室外风气候特性、室内自然通风情况的模拟分析研究。得到了住宅小区室外风速、风压的分布场、室内三维速度场、温度场分布场。探讨了风向、风速、窗户对局部气候的影响。研究表明对室外风环境,由于小区建筑的分布特征,存在着局部增强的强风区,最大速比达到1.8;就室内气候而言,具有自然对流效果的A型房间的自然通风效果要优于B型房间。通过对既有城市住宅小区的室内外气候环境的模拟分析,可以为建筑气候的设计提供重要的参考价值。     

Simulation of a localized heating system for broiler brooding to improve energy performance

The aim of this work is to evaluate the performance of an innovative localized solar‐assisted pen heating system for brooding using a 3D computational simulation model of the heated space. The warm air‐curtained pen ensures acceptable temperature, air velocity, relative humidity, and air quality that meet the ventilation and heat requirements for a typical pen of 100 chicks as recommended by the American Society of Heating Refrigeration and Air Conditioning Engineers and American Society of Agricultural and Biological Engineers. The supply flow characteristics and the simulated velocity and temperature field of the curtained region were determined such that they meet the ventilation requirements and comfort criteria. Results show that air supplied at 40°C is capable of delivering the desired microenvironment at bird level while the heat input to the unit is 685 W when outdoor temperature is ?5°C. The system's energy performance was then analyzed using a prototype of 16 pens. The energy consumption of the new heating scheme consumed one third of the energy required by conventional non‐localized system. Moreover, integrating the new design with a solar system utilizing parabolic concentrators provided 72% of the power load from solar energy during a winter flock operation and 100% during other seasons. Copyright © 2013 John Wiley & Sons, Ltd.