喷射式混合加热器在供热系统中的应用与节能

介绍喷射式混合加热器的使用性能,在蒸汽供热系统中的应用,以及在节能方面的一些应用.     

低温循环水供热系统节能运行的误区与对策

从供热系统泵站设计、运行、维护等方面提出泵站的节能方法,对同类供热企业节能降耗具有借鉴意义。     

小火电凝汽机组采用循环水供热势在必行

小火电凝汽机组采用循环水供热势在必行赵念平最近，我国国民经济和社会发展＂九五＂计划和２０１０年远景目标纲要再一次提出＂能源工业应坚持节约与开发并举，把节约放在首位＂的能源利用政策。可以预见，这一政策必将推动我国各项节能工作向更快更深的方向发展，从而使...     

冷凝式汽轮机循环水供热改造分析

小型冷凝式发电用汽轮机在我国北方地区目前仍普遍存在，在其安全发电的同时，存在着能耗高，经济性差的缺点。本文对造成经济性差的主要原因进行了分析，并讨论了提高能源利用率，降低小型汽轮机组冷源损失的方法。     

混合式加热器的发展及应用

混合式加热器是换热器的一种,应用的目的是用高温介质加热低温介质。它不同于间接式加热器的高温介质和低温介质隔开,而是两种介质相互混合。在工业生产及日常生活中,允许高温介质和低温介质混合使用的场合很多,因此为混合式加热器的使用提供了巨大的市场。     

高压加热器疏水自动化的节能

一、前言 我厂一期工程共有两台ZJ—110G型高压加热器(简称高加)。自1986年投运至今五年来,高加一直处在假水位(实际是无水位)运行状态,使得高加疏水带汽,不仅浪费了加热蒸汽,还会影响除氧器的正常运行。高加疏水自动化的投入,可以使高加保持一定的低水位,杜绝疏水带汽,达到节能降耗的目的。本文主要介绍我厂高加疏水自动调节系统的更改方案与投试经验。     

循环水供热在分布式能源站的应用

在分布式能源站中采用循环水供热方案,将低品位的乏汽换成热水供给用户,符合分布式能源系统"能源梯级利用"的原则,能极大的提高分布式能源站的热效率。介绍了分布式能源系统中采用循环水供热的理论分析,并对具体工程进行计算,最后指出分布式能源站中使用循环水供热的优缺点和适用范围。     

电厂循环水水源热泵供热系统的热经济性研究

为研究电厂循环水水源热泵供热系统的热经济性,建立了热泵供热系统计算模型,对循环水水源热泵供热与抽汽供热两种方式进行了热经济性比较,引入单位供热负荷功耗差指标定量表征热泵供热的热经济性,提出了采用循环水水源热泵进行供热的可行性判据。对某200 MW典型机组进行了计算,发现供热温度越低、供热负荷越小、供热抽汽压力越大、制热循环效率越高,电厂采用循环水水源热泵供热的可行性越好。     

解决热水系统氧腐蚀问题的研究

根据本单位既有蒸汽锅炉,又有热水锅炉的实际情况,介绍了综合利用,分项治理,有效控制热水系统氧腐蚀的方法。     

System performance and economic analysis of solar-assisted cooling/heating system

The long-term system simulation and economic analysis of solar-assisted cooling/heating system (SACH-2) was carried out in order to find an economical design. The solar heat driven ejector cooling system (ECS) is used to provide part of the cooling load to reduce the energy consumption of the air conditioner installed as the base-load cooler. A standard SACH-2 system for cooling load 3.5 kW (1 RT) and daily cooling time 10 h is used for case study. The cooling performance is assumed only in summer seasons from May to October. In winter season from November to April, only heat is supplied. Two installation locations (Taipei and Tainan) were examined.It was found from the cooling performance simulation that in order to save 50% energy of the air conditioner, the required solar collector area is 40 m² in Taipei and 31 m² in Tainan, for COP_j = 0.2. If the solar collector area is designed as 20 m², the solar ejector cooling system will supply about 17–26% cooling load in Taipei in summer season and about 21–27% cooling load in Tainan. Simulation for long-term performance including cooling in summer (May–October) and hot water supply in winter (November–April) was carried out to determine the monthly-average energy savings. The corresponding daily hot water supply (with 40 °C temperature rise of water) for 20 m² solar collector area is 616–858 L/day in Tainan and 304–533 L/day in Taipei.The economic analysis shows that the payback time of SACH-2 decreases with increasing cooling capacity. The payback time is 4.8 years in Tainan and 6.2 years in Taipei when the cooling capacity >10 RT. If the ECS is treated as an additional device used as a protective equipment to avoid overheating of solar collectors and to convert the excess solar heat in summer into cooling to reduce the energy consumption of air conditioner, the payback time is less than 3 years for cooling capacity larger than 3 RT.     

基于Modelica的供热系统用复合相变储热单元的热性能分析

针对高背压供热改造机组的高热电耦合性问题,提出通过配置多级压缩膨胀石墨和石蜡复合相变储热装置的方式,实现热电解耦,并且基于Modelica非因果建模语言在Dymola平台上,详细分析了该装置的热性能,为其设计提供了依据。     

Thermal and economical analysis of a central solar heating system with underground seasonal storage in Turkey

Thermal performance and economic feasibility of two types of central solar heating system with seasonal storage under four climatically different Turkey locations are investigated. The effects of storage volume and collector area on the thermal performance and cost are studied for three load sizes. The simulation model of the system consisting of flat plate solar collectors, a heat pump, under ground storage tank and heating load based on a finite element analysis and finite element code ANSYS™ is chosen as a convenient tool. In this study, the lowest solar fraction value for Trabzon (41°N) and the highest solar fraction value for Adana (37°N) are obtained. Based on the economic analysis, the payback period of system is found to be about 25–35 years for Turkey.     

Thermal performance analysis of a phase change thermal storage unit for space heating

This paper presents the results of a comprehensive numerical study on the thermal performance of an air based phase change thermal storage unit (TSU) for space heating. The unit is designed for integration into space heating and cooling systems. The unit consists of a number of one dimensional phase change material (PCM) slabs contained in a rectangular duct where air passes between the slabs. The numerical analysis was based on an experimentally validated model. A parametric study has been carried out including the study on the effects of charge and discharge temperature differences, air mass flow rate, slab thicknesses, air gaps and slab dimensions on the air outlet temperatures and heat transfer rates of the thermal storage unit. The paper introduces and discusses quantities called charge and discharge temperature differences which play an important role in the melting and freezing processes.     

Thermal performance of PCM thermal storage unit for a roof integrated solar heating system

The thermal performance of a phase change thermal storage unit is analysed and discussed. The storage unit is a component of a roof integrated solar heating system being developed for space heating of a home. The unit consists of several layers of phase change material (PCM) slabs with a melting temperature of 29 °C. Warm air delivered by a roof integrated collector is passed through the spaces between the PCM layers to charge the storage unit. The stored heat is utilised to heat ambient air before being admitted to a living space. The study is based on both experimental results and a theoretical two dimensional mathematical model of the PCM employed to analyse the transient thermal behaviour of the storage unit during the charge and discharge periods. The analysis takes into account the effects of sensible heat which exists when the initial temperature of the PCM is well below or above the melting point during melting or freezing. The significance of natural convection occurring inside the PCM on the heat transfer rate during melting which was previously suspected as the cause of faster melting process in one of the experiments is discussed. The results are compared with a previous analysis based on a one dimensional model which neglected the effect of sensible heat. A comparison with experimental results for a specific geometry is also made.     

Thermal performance of combined solar and pellet heating systems

Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems. System 1 and 2 with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The often lower efficiency of pellet heaters compared to oil or gas heaters increases the final energy demand. Consequently, heat losses of the various systems have been studied. The systems have been modeled in TRNSYS and simulated with parameters identified from measurements. For almost all systems the flue gas losses are the main heat losses except for system 3 where store heat losses prevail. Relevant are also the heat losses of the burner and the boiler to the ambient. Significant leakage losses are noticed for system 3 and 4. For buildings with an open internal design system 1 is the most efficient solution. Other buildings should preferably apply system 2 or 3. The right choice of the system depends also on whether the heater is placed inside or outside of the heated area. Unlike the expectations and results from other studies, the operation of the pellet heaters with modulating combustion power is not necessarily improving the performance. A large potential for system optimisation exists for all studied systems, which when applied could alter the relative merits of the different system types.     

水源热泵供暖系统性能分析及优化建议

以北方某住宅建筑应用水源热泵供暖项目为例,测试该系统冬季供暖运行状况,并对测试的结果进行分析,计算系统的能效比以及系统各部分的能耗状况。根据测试结果以及系统的实际运行状况提出合理性的改进建议。     

环境条件对全玻璃真空太阳能热水系统热性能的影响

对同一太阳能热水系统在不同环境条件下得热量和热损的多次试验,计算了系统标准单位轮廓采光面积的日有用得热量和平均热损因数,并分析了太阳辐射量、环境风速和温度对系统得热量和热损的影响规律。     

Thermal analysis of indirect geothermal district heating systems

Low- and moderate-temperature geothermal resources have been discovered in many areas of the world, and are being used increasingly for district heating. Due to the corrosive action of some geothermal waters, heat exchangers are used to avoid circulating the geothermal fluid directly through the district heating systems, in what are called Indirect Geothermal District Heating Systems (IGDHS). In this case, the geothermal water acts as a heat source directly heating the network fluid through a heat exchanger. However, it is different from that of conventional systems in which hot water from a fossil fuel boiler is used directly. In the former (IGDHS), the geothermal water is regarded as a heat source with constant temperature, and in the latter the boiler is considered a heat source with variable heat flux. This paper presents a thermal analysis of a simple IGDHS, and discusses the selection of heat exchangers and optimum operating conditions.