Optimization of Selecting Air Conditioning Cold/Heat Sources with Grey Relation Analysis

Selection of air conditioning（AC） cold/heat sources generally concerns about certain aspects and cannot reveal the whole profile of the problems. Grey relation analysis （GRA） is a data processing method to categorize the correlation extent of compared sequences and a certain reference sequence in a system with uncertain information. It is applied to evaluating and selecting AC cold/heat sources from four main aspects, which are technology, economy, reliability, and operation and management. Case study shows that the result for selecting AC cold/heat sources with the GRA method can be more reasonable and convincible. Thus it offers a new approach for designers in heating, ventilating and air conditioning field to compare and evaluate different AC cold/heat sou rces.

Field experimental study on the cooling effect of mine cooling system acquiring cold source from return air

With the increase of mining depth, more and deeper coal mines are limited by heat disaster. The cooling energy in deep mine cooling system comes from mine water inrush or ground cooling tower, but we cannot adopt the two methods because mine water inrush in many old coal mines in China is limited. What is more, the cooling pipelines cannot be put in narrow pit-shaft. To settle the problem above, according to the characteristics of Zhangxiaolou Coal Mine, this paper adopts the deep mine return air as the cooling energy for deep mine cooling system. In addition, we carried out cite test to extract cold energy from return air. Through monitoring the water quantity, water temperature of cooling system and air temperature, we got the thermodynamic equilibrium parameters during the cooling energy acquisition analysis and the effect of cooling system that the temperature and humidity on working face are respectively reduced to 8-12 ℃ and 8-15% through cooling. This research offers experimental reference for deep mine cooling which lacks cooling energy.

Thermal partition of two asymmetric discrete heat sources by cold air curtain

A partition solution implemented by a cold air curtain for two asymmetric discrete heat sources in a twodimensional rectangular enclosure was numerically studied. Main attentions were focused on the effects of Reynolds number, Grashof number, separation distance between heat sources, and buoyancy ratio. It is found that the airflow and heat transfer are not only determined by governing parameters, but also affected by boundary conditions. It is also found that nearly symmetry of flow structure corresponds to nearly thermal partition, and the symmetry can be enhanced when Reynolds number, separation distance and buoyancy ratio increase. In addition, it is observed that there is a minimum Reynolds number for obtaining nearly thermal partition, which increases when Grashof number increases.

Applicability of sewage heat pump air-conditioning system

A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. The theoretical and quantitative calculations indicate that sewage flux in the city sewage main pipe in the project can satisfy heat exchange requirements,and taking water from the pipes has relatively small influence on the pipe net in summer and winter. The sewage heat pump air-conditioning system can save 21.5% operating cost in one year,which is energy efficient and environmentally friendly.

Characteristic studies of heat sources and performance analysis of free-cooling assisted air conditioning and ventilation systems for working faces of mineral mines

High temperature heat hazard at mineral mine becomes more and more serious as the increase of mining depth.Heat sources at working faces of mineral mines are complex and are of different characteristics,presenting new challenges for air conditioning systems.In this paper,heat sources at four types of working faces are summarized and their characteristics are investigated.Based on this,simplified equations,which are linear with length of working faces,are proposed to calculate heat dissipation rates.So that the main heat sources of different working faces can be found,and cooling load of air conditioning systems can be calculated.Then,considering main heat sources of coal mines,a typical working face is designed to investigate performances of different ventilation systems and air conditioning systems.Simulation results show that segmented ventilation systems(SC)and heat shield assisted centralized ventilation systems(CCHS)can realize much better temperature distributions at working faces.However,cooling load can be greatly reduced for CCHS,when untreated air is supplied to the coal seam side.Based on this,free cooling assisted air conditioning systems are designed,and annual average energy efficiency ratio(EERann)of the systems are investigated and compared between direct evaporate cooling and indirect evaporate cooling(IEC).For SC,as compared with scenarios without free-cooling,IEC can increase EERann by 15%-23%and 22%-32%under Benxi and Datong ambient conditions,respectively.Besides,to ensure high EERann,CCHS is preferred and it is essential to increase thermal insulation of air ducts.

Experimental Study of Energy-Saving Air-Conditioner with Hot Water

Energy-saving air-conditioner with hot water is an air source heat pump air-conditioner,which can also supply hot water.The hot water is heated by a double pipe condenser connected with an air-cooled condenser in series in the system.This experiment of the energy-saving air-conditioner was carried out in the enthalpy-difference air-conditioner laboratory.The hot water temperature and the compressor's discharge and suction pressure were recorded in the working condition,where the ambient temperature was at 43 ℃,35 ℃,21 ℃,7 ℃,and 2 ℃ separately.The results showed that the system operated stably and reliably.This system can supply 240 L hot water at 50 ℃ in the whole year,and its coefficience of performance(COP)is much higher than the conventional air source heat pump system.Its energy conservation was proved by comparing the thermal efficiency with other sourece water heaters.

太阳能-空气源热泵牧草干燥系统制热性能研究

以太阳能-空气源热泵牧草干燥系统为研究对象,通过系统不同工作模式的温升、恒温制热试验及带载试验,分析了温升速率、单位温升能耗、COP及除湿效率。研究结果表明:联合制热模式与太阳能单独制热相比,单位温升耗电量降低了86.2%,温升速率提高了99~112倍。联合制热模式与热泵单独制热试验相比,在温升过程中温升速率降低了7.7%~17.6%,单位温升耗电量降低8.0%;在恒温制热过程中,前者COP比后者提高了6.5%~11.1%,耗电量降低了5.8%~10.7%;在升温制热过程中前者COP比后者提高了6.0%~10.4%,耗电量降低了6.6%~11.1%。联合干燥模式比热泵单独干燥模式的SMER值高19.8%~36.2%。

严寒地区空气源热泵耦合电磁能系统模拟运行研究

目的 为了促进空气源热泵耦合电磁能供热系统在严寒地区住宅建筑中的应用,研究该系统的运行性能和稳定性。方法 以沈阳地区某住宅建筑为例,应用Trnsys软件建立了空气源热泵耦合电磁能供热系统仿真模型,并用实测值对模型进行了验证;深入探讨空气源热泵耦合电磁能供热系统在供热期的运行特点,并与空气源热泵和电磁能供热系统分别进行比较。结果 空气源热泵耦合电磁能供热系统模型可靠,相对误差可以控制在15%以内;在供热期,室内平均温度可保持在17.97~21.84℃;空气源热泵耦合电磁能供热系统比电磁能供热系统的COP提高了59.17%,空气源热泵耦合电磁能供热系统CO_(2)减排量比空气源热泵和电磁能供热系统分别提高1.47%和59.50%。结论 空气源热泵耦合电磁能供热系统运行和COP变化更为稳定,系统环境效益更佳,室内热舒适性更高。

Cold Storage Capacity for Solar Air-Conditioning in Office Buildings in Different Climates

The building sector accounts for more than 40% of the global energy consumption. This consumption may be lowered by reducing building energy requirements and using renewable energy in building energy supply systems. Solar air-conditioning systems(SACS) are a promising solution for the reduction of conventional energy in buildings. The storage, especially the cold storage, plays an important role in SACS for unstable solar irradiation. In this paper, we took the absorption refrigerating unit as an example, and the solar air-conditioning system of an office building in Beijing was simulated. The accuracy of this model was verified by comparing with the SACS operation data. Moreover, based on the simulation data, the cold storage capacity of the solar air-conditioning system in different climatic regions was studied. The cold storage capacities of SACS in 20 cities distributed in different climate regions were studied systematically. The results simulated by our proposed model will be beneficial to the SACS design, and will enlarge the application of SACS.

光伏光热联合双源热泵系统运行模式研究(1):最佳切换模式验证

讨论了光伏光热联合双源热泵系统制热运行的最佳切换模式。利用TRNSYS软件建立了仿真模型,对双源(水源、空气源)热泵系统性能系数(COP_(s))进行了计算,提出以某时刻空气源热泵模式或水源热泵模式运行COP_(s)较大者优先运行作为COP_(s)切换模式。通过前期实验结果验证了模拟结果的正确性,并与常规的集热水箱温度切换模式进行了对比实验,验证了COP_(s)切换模式的有效性。结果表明,该实验系统以COP_(s)最佳切换模式运行时发电量和发电效率较集热水箱温度切换模式分别提高了5.35%和1.73%,耗电量降低了17.03%,COP_(s)提高了4.91%。

超低温空气源热泵与太阳能供热系统在寒冷地区的优化应用

为了加强对环境的保护,推动可持续发展社会的建设,超低温空气源热泵联合太阳能供热系统被研发出来。该联合系统的应用极大地缓解了当前能源紧张的问题,同时对降低环境污染、提高能源利用率、降低供暖成本也有着积极的作用。基于此,围绕超低温空气热源泵与太阳能供热系统展开论述,对当前超低温空气源热泵与太阳能联合供热系统结构进行分析,剖析其中所存在的问题,同时针对问题提出超低温空气源热泵与太阳能供热系统的优化方案,将其应用于北方寒冷地区的一建筑当中,并对应用效果进行分析。

新型智能化纺纱车间环境的优化措施

针对智能化纺纱车间规模大、自动化程度高、生产集约化、发热强度高的特点,提出了优化新型智能化纺纱车间环境的系列策略和措施。分析了影响车间温湿度、气流组织、空气清洁度的因素。通过采取稳定各工序半成品回潮率,提高空调除尘设备能效,强化均匀送吸风等,采用细纱车间热分流、热转移、除尘空调系统低能耗联动等方法,实现了对纺纱车间环境的优化,并配备完善的火灾自动报警和自动灭火系统,保持了车间环境的安全。认为:纺纱车间环境优化的实施可以满足新型智能化纺纱生产线的高效、绿色生产。

考虑变掺氧富氧燃烧与利用LNG冷能的LAES的综合能源系统低碳经济调度

为促进风电消纳,减少火电机组的碳排放,解决综合能源系统(Integrated Energy System,IES)低碳经济运行问题,文中引入变掺氧富氧燃烧技术对燃气机组进行改造,并结合利用液化天然气(Liquefied Natural Gas,LNG)冷能的液化空气储能(Liquid Air Energy Storage,LAES),提出了一种电热气冷IES低碳经济优化策略。首先,构建含变掺氧富氧燃烧燃气机组、利用LNG冷能的LAES、电转气(Power To Gas,P2G)设备、中央空调和溴化锂制冷机的IES架构,并建立各设备的数学模型;其次,引入阶梯式碳交易机制,建立了以系统运行成本最小为目标的电热气冷IES低碳经济调度模型;最后,采用MATLAB调用GUROBI求解器对多个场景进行求解,验证了文中提出的低碳经济优化调度策略可以提高系统的风电消纳、有效降低系统运行成本,实现碳减排。

太阳能-空气源热泵热水系统新型组合优化设计

太阳能-空气源热泵热水系统(solar-air source heat pump hot water system, SAHWS)常用于宿舍楼宇供暖,通过对系统参数的优化设计可显著提高系统能效性能与环境友好性。为得到一种综合考虑SAHWS经济、能源、环保与节能的优化方法,提出了一种新型组合优化设计策略,并利用TRNSYS软件搭建系统仿真模型,以西安、西宁、拉萨这3座不同太阳能资源等级城市为例,对SAHWS运行工况对比分析。结果表明:与常用生命周期成本设计相比,所提出的组合优化设计不仅降低了系统成本,还有着较低的系统能耗;组合优化设计的热泵能耗与工作小时数最短,且有最低的热损,在投资成本、系统季节性能因子、太阳能保证率以及碳粉尘、二氧化碳排放量均有较好表现。

浅谈新能源汽车空调系统的组成特点

在燃油汽车中,空调系统的制热是利用发动机的冷却水来进行热交换的,属于废热利用,是不会额外增加燃油消耗量的。制冷系统是由发动机驱动空调压缩机进行制冷的。而在新能源汽车中,由于其结构的特殊性,其空调系统的组成与传统燃油车有着较大的不同。空调制冷采用了由电机驱动空调压缩机来实现制冷。但制热系统的组成却形式多样。制热系统有采用发动机冷却水制热的(混动车型),有采用PTC电加热的(纯电和插混),有采用热泵式制热系统的,还有的是多种制热系统的组合等。

回热器对CO_(2)驻车空调系统制热性能影响的研究

为了提升驻车空调的制热性能,搭建了一套带回热器的跨临界CO_(2)驻车空调系统,在焓差室中实验研究了有无回热器时气冷器出口温度与排气压力对系统的性能影响。结果表明:在排气压力分别为8.5、9.0、9.5 MPa时,气冷器出口温度从20℃升高至35℃时,制热COP_(h)降低幅度分别为29.7%、19.9%、16.4%;系统使用回热器后最优排气压力下降,下降幅度分别为4.4%、6.1%,对应的最大COP_(h)增加幅度分别为3.2%、3.7%。通过曲面拟合得到了系统使用回热器时提升制热性能的排气压力与气冷器出口温度关联式,该式对回热器在跨临界CO_(2)驻车空调系统制热模式下的实际应用有一定指导意义。

某超高层建筑空调冷源系统技术经济性分析

对于超高层建筑,其常用的空调系统为传统的空调水系统形式,以位于深圳的某超高层建筑为研究对象,基于超高层建筑的空调水系统需要竖向分区的特点,以常规集中式系统和竖向分布式系统为研究对象,探讨了这两种系统形式空调冷源的设备配置、初投资、运行费用、土建需求和竖向运输等方面的内容,得到了该超高层建筑适宜采用竖向分布式系统的空调冷源方案。

基于蓄热装置辅助的燃料电池电动车供暖系统动态仿真

为了辅助燃料电池车辆预热,提升燃料电池在低温下的冷启动速率以及降低电动车能耗,该文提出了一种基于热泵和蓄热装置联合的燃料电池电动车供暖方案,并开展了燃料电池车辆系统动态仿真研究,对比了有无蓄热装置辅助的系统对车辆运行过程的影响。结果表明:在寒冷运行环境下,蓄热装置可确保驾驶循环工况下循环冷却液热量来源的连续性,相较于无蓄热装置的热管理系统,热泵和蓄热联合供暖方案可使空调系统能耗下降26%;利用蓄热装置辅助的供暖系统能够改善燃料电池电动车的冬季冷启动特性,优化车辆电池系统的热管理。

融霜工况影响下空气源热泵机组频率控制系统

空气源热泵机组在融霜工况下,由于外部环境温度低,机组内部的水箱和管路可能会结霜,导致传热效率下降、能耗增加,使得频率控制不精准。为此,设计融霜工况影响下空气源热泵机组频率控制系统。设计PLC频率控制结构、频率控制中央处理器与PID控制阀门,联合控制热源侧水泵变频。计算机组结霜量,获取换热器的有效集热量。基于分段调节思想,利用计算机调整侧水泵出水量和调节参数,计算融霜启动调频速度。由实验结果可知,所设计系统在不同融霜工况下控制效果与实际最为接近,控制结果误差最大仅为0.1 Hz,能够实现精准控制频率。

北京某大型商场空调系统节能改造方案分析

大型商场人流量大、散热设备多、空调系统运行时间长,有较大节能潜力。调研了北京某大型商场空调系统的能耗情况,针对其运行过程存在的问题,提出了一套基于空调系统节能控制技术的综合节能改造方案。研究表明,该空调系统节能改造后,年节电量为140.56万k Wh,每年节省电费160.24万元;节热量为601.82GJ,每年节省供热费用5.95万元,节能效果与经济效益较好,可为北京地区类似公建节能改造提供借鉴和参考。