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1、外文翻译The Applications of Heat pumps1.Heat pumps in industry 1). SystemsRelatively few heat pumps are currently installed in industry. However, as environmental regulations become stricter, industrial heat pumps can become an important technology to reduce emissions, improve efficiency, and limit the
2、use of ground water for cooling To ensure the sound application of heat pumps in industry, processes should be optimised and integrated. Through process integration improved energy efficiency is achieved by thermodynamically optimising total industrial processes. An important instrument for process
3、integration is pinch analysis, a technology to characterise process heat streams and identify possibilities for heat recovery. Such possibilities may include improved heat exchanger networks, cogeneration and heat pumps. Pinch analysis is especially powerful for large, complex processes with multipl
4、e operations, and is an excellent instrument to identify sound heat pump opportunities. Industrial applications show a great variation in the type of drive energy, heat pump size, operating conditions, heat sources and the type of application. The heat pump units are generally designed for a specifi
5、c application, and are therefore unique. The major types of industrial heat pumps are: o Mechanical vapour recompression systems (MVRs), classified as open or semi-open heat pumps. In open systems, vapour from an industrial process is compressed to a higher pressure and thus a higher temperature, an
6、d condensed in the same process giving off heat. In semi-open systems, heat from the recompressed vapour is transferred to the process via a heat exchanger. Because one or two heat exchangers are eliminated (evaporator and/or condenser) and the temperature lift is generally small, the performance of
7、 MVR systems is high, with typical coefficients of performance (COPs) of 10 to 30. Current MVR systems work with heat-source temperatures from 70-80篊, and deliver heat between 110 and 150篊, in some cases up to 200篊. Water is the most common working fluid (i.e. recompressed process vapour), although
8、other process vapours are also used, notably in the (petro-) chemical industry. o Closed-cycle compression heat pumps are described in the section Heat pump technology . Currently applied working fluids limit the maximum output temperature to 120篊. o Absorption heat pumps (Type I) are not widely use
9、d in industrial applications. Some have been realised to recover heat from refuse incineration plants, notably in Sweden and Denmark. Current systems with water/lithium bromide as working pair achieve an output temperature of 100篊 and a temperature lift of 65篊. The COP typically ranges from 1.2 to 1
10、.4. The new generation of advanced absorption heat pump systems will have higher output temperatures (up to 260篊) and higher temperature lifts. o Heat transformers (Type II) have the same main components and working principle as absorption heat pumps. With a heat transformer waste heat can be upgrad
11、ed, virtually without the use of external drive energy. Waste heat of a medium temperature (i.e. between the demand level and the environmental level) is supplied to the evaporator and generator. Useful heat of a higher temperature is given off in the absorber. All current systems use water and lith
12、ium bromide as working pair. These heat transformers can achieve a delivery temperatures up to 150篊, typically with a lift of 50篊. COPs under these conditions range from 0.45 to 0.48. o Reverse Brayton-cycle heat pumps recover solvents from gases in many processes. Solvent loaden air is compressed,
13、and then expanded. The air cools through the expansion, and the solvents condense and are recovered. Further expansion (with the associated additional cooling, condensation and solvent recovery) takes place in a turbine, which drives the compressor. 2). ApplicationsIndustrial heat pumps are mainly u
14、sed for: o space heating; o heating and cooling of process streams; o water heating for washing, sanitation and cleaning; o steam production; o drying/dehumidification; o evaporation; o distillation; o concentration. When heat pumps are used in drying, evaporation and distillation processes, heat is
15、 recycled within the process. For space heating, heating of process streams and steam production, heat pumps utilise (waste) heat sources between 20篊 and 100篊. The most common waste heat streams in industry are cooling water, effluent, condensate, moisture, and condenser heat from refrigeration plan
16、ts. Because of the fluctuation in waste heat supply, it can be necessary to use large storage tanks for accumulation to ensure stable operation of the heat pump. o Space heating:Heat pumps can utilise conventional heat sources for heating of greenhouses and industrial buildings, or they can recover
17、industrial waste heat that could not be used directly, and provide a low- to medium temperature heat that can be utilised internally or externally for space heating. Mainly electric closed-cycle compression heat pumps are used. o Process water heating and cooling:Many industries need warm process wa
18、ter in the temperature range from 40-90篊, and often have a significant hot water demand in the same temperature range for washing, sanitation and cleaning purposes. This can be met by heat pumps. Heat pumps can also be a part of an integrated system that provides both cooling and heating. Mainly ele
19、ctric closed-cycle compression heat pumps are installed, but a few absorption heat pumps and heat transformers are also in use. o Steam production:Industry consumes vast amounts of low-, medium- and high-pressure steam in the temperature range from 100-200篊. Steam is used directly in industrial proc
20、esses, and for heat distribution. Current high temperature heat pumps can produce steam up to 150篊 (a heat pump prototype has achieved 300篊). Both open and semi-open MVR systems, closed-cycle compression heat pumps, cascade (combination) systems and a few heat transformers are in operation. o Drying
21、 process:Heat pumps are used extensively in industrial dehumidification and drying processes at low and moderate temperatures (maximum 100篊). The main applications are drying of pulp and paper, various food products wood and lumber. Drying of temperature-sensitive products is also interesting. Heat
22、pump dryers generally have high performance (COP 5-7), and often improve the quality of the dried products as compared with traditional drying methods. Because the drying is executed in a closed system, odours from the drying of food products etc. are reduced. Both closed-cycle compression heat pump
23、s and MVR systems are used. o Evaporation and distillation processes:Evaporation and distillation are energy-intensive processes, and most heat pumps are installed in these processes in the chemical and food industries. In evaporation processes the residue is the main product, while the vapour (dist
24、illate) is the main product in distillation processes. Most systems are open or semi-open MVRs, but closed-cycle compression heat pumps are also applied. Small temperature lifts result in high performance with COPs ranging from 6 to 30.2Heat pumps in residential and commercial buildings1）.FunctionsH
25、eat pumps for heating and cooling buildings can be divided into four main categories depending on their operational function: o Heating-only heat pumps, providing space heating and/or water heating. o Heating and cooling heat pumps, providing both space heating and cooling.The most common type is th
26、e reversible air-to-air heat pump, which either operates in heating or cooling mode. Large heat pumps in commercial/institutional buildings use water loops (hydronic) for heat and cold distribution, so they can provide heating and cooling simultaneously. o Integrated heat pump systems, providing spa
27、ce heating, cooling, water heating and sometimes exhaust air heat recovery.Water heating can be by desuperheating only, or by desuperheating and condenser heating. The latter permits water heating when no space heating or cooling is required. o Heat pump water heaters, fully dedicated to water heati
28、ng.They often use air from the immediate surroundings as heat source, but can also be exhaust-air heat pumps, or desuperheaters on air-to-air and water-to-air heat pumps. Heat pumps can be both monovalent and bivalent, where monovalent heat pumps meet the annual heating and cooling demand alone, whi
29、le bivalent heat pumps are sized for 20-60% of the maximum heat load and meet around 50-95% of the annual heating demand (in a European residence). The peak load is met by an auxiliary heating system, often a gas or oil boiler. In larger buildings the heat pump may be used in tandem with a cogenerat
30、ion system (CHP).In residential applications room heat pumps can be reversible air-to-air heat pumps (ductless packaged or split type units). The heat pump can also be integrated in a forced-air duct system or a hydronic heat distribution system with floor heating or radiators (central system). In c
31、ommercial/institutional buildings the heat pump system can be a central installation connected to an air duct or hydronic system, or a multi-zone system where multiple heat pump units are placed in different zones of the building to provide individual space conditioning. Efficient in large buildings
32、 is the water-loop heat pump system, which involves a closed water loop with multiple heat pumps linked to the loop to provide heating and cooling, with a cooling tower and auxiliary heat source as backup. The different heat sources that can be used for heat pumps in residential and commercial build
33、ings are described in the section Heat sources. The next paragraph describes the types of heat and cold distribution systems that can be used in buildings.2). Heat and cold distribution systemsAir is the most common distribution medium in the mature heat pump markets of Japan and the United States.
34、The air is either passed directly into a room by the space-conditioning unit, or distributed through a forced-air ducted system. The output temperature of an air distribution system is usually in the range of 30-50C. Water distribution systems (hydronic systems) are predominantly used in Europe, Can
35、ada and the north eastern part of the United States. Conventional radiator systems require high distribution temperatures, typically 60-90C. Todays low temperature radiators and convectors are designed for a maximum operating temperature of 45-55C, while 30-45C is typical for floor heating systems.
36、Table 1 summarises typical temperature requirements for various heat and cold distribution systems. Table 1: Typical delivery temperatures for various heat and cold distribution systems.ApplicationSupply temperature range(C)Air distributionAir heating30 - 50Floor heating; low temperature (modern)30
37、- 45Hydronic systemsradiators45 - 55High temperature (conventional) radiators60 - 90District heating - hot water70 - 100District heatingDistrict heating - hot water/steam100 - 180Cooled air10 - 15Space coolingChilled water5 - 15District cooling5 - 8Because a heat pump operates most effectively when
38、the temperature difference between the heat source and heat sink (distribution system) is small, the heat distribution temperature for space heating heat pumps should be kept as low as possible during the heating season. Table 2 shows typical COPs for a water-to-water heat pump operating in various
39、heat distribution systems. The temperature of the heat source is 5C, and the heat pump Carnot efficiency is 50%. Table 2: Example of how the COP of a water-to-water heat pump varies with the distribution/return temperature.Heat distribution system (supply/return temperature)COPConventional radiators
40、 (60/50C)2.5Floor heating (35/30C)4.0Modern radiators (45/35C)3.5热泵的应用1热泵在工业上的应用1）系统目前，在工业领域当中只有较少的热泵得到运用。但，随着环境要求的逐步的提高，工业热泵变成一种可以用来减少散发，提高效率以及在制冷过程中限制地下水过多使用的重要的技术。在总的工业流程中，能效的提高是通过综合处理由热力状态来完成的。因此，为了确保热泵在工业中的充分利用，这就需要合理、全面的处理。挤压分析是综合处理中的一种重要的方法，这种技术能表现出处理热的趋势和鉴定热回收的可行性，可行性包括改善热交换网络和热泵。挤压式分析对大型复杂的
41、综合控制过程是特别有效的，并且是一种一个挑选适合的热泵的机会。在工业应用上，热泵已经在运行能源的形式、型号、控制条件、热源和应用方式上等许多方面都发生了很大的变化。热泵各个组成部分通常是为了一个特殊的应用而设计的，因此热泵也是独特的。工业热泵的主要形式有： 机械蒸汽压缩系统（MVRs），可分为开式和半开式热泵系统。在开式系统中，来自工业过程的蒸汽被压缩到高温高压，并且在同样的过程中冷凝放热。在半开式系统中，来自压缩蒸汽的热量被传递到一个热交换机中。因为减少一个或两个热交换机（蒸发器和/或冷凝器）只能得到很小的温升，但是MVR系统却有较高的性能，性能系数（COPs）可达1030。通用的MVR系统
42、的工作热源温度在7080oC，释放的热量在110150 oC，在特定情况下能达到200 oC。水是最普通的“工作流体”（即压缩过程蒸汽），虽然在另一些过程蒸汽也被用，特别是在化学工业中最为明显。 闭式循环压缩热泵在热泵技术这一部分介绍。当前提供的最大工作流体温度为120 oC。 吸收式热泵在工业上没有得到广泛的应用，但是一些专家已经意识到从废弃的焚化植物中取得热量，尤其是在瑞典和丹麦。当前水/溴化锂系统工作部分的输出温度能达到100oC并且有65oC的温升。有代表性的COP范围是1.21.4。最近研制出的先进的吸收式热泵系统具有更高的输出温度（达到260oC）和更高的温升。 热交换器（型）和吸
43、收式热泵的组成部分和工作原理是一样的，都通过热交换器，实质上不需要外部的驱动能。中间温度（即在要求的标准和环境标准之间）的废热可以用来提供给蒸发器和发生器。有用的高温热在吸收器中放出。当前所有的系统都能够用水和溴化锂来作为工质。这些传热装置能达到一个150 oC的传递温度，50 oC的温升。在这些条件下的COP的范围在0.450.48之间。 布雷顿热泵循环可以在许多过程中的蒸汽中回收溶剂。载有空气的溶剂先被压缩然后释放。空气通过发生器得以冷却，溶剂被冷凝和被回收。然后再把溶剂在涡轮机里膨胀（传统的制冷，冷凝和溶剂回收的综合），使涡轮机驱动压缩机。2）应用工业热泵主要用于： 空间加热； 过程处理
44、的供热和制冷； 用业洗涤、公共卫生、清洁用的水加热； 蒸汽生产； 干燥/除湿； 蒸发； 蒸馏； 浓缩。当在干燥、蒸发、蒸馏过程中使用热泵时，热量可以在此过程中被循环利用。而在空间加热，过程加热和蒸汽生成的热能，在20100 oC之间的热源被热泵利用。 在工业中大部分废热物是冷水、流出物、冷凝物、湿气和来自冷藏车间的冷凝热。由于提供的废热的波动，必须用较大的储藏箱去储藏这些热量，才能确保热泵的稳定运行。 空间加热：热泵能利用传统的热源来给温室和工业建筑供热，或者也可以重新利用那些不能被直接利用的工业废热，并且提供一个低于中间温度的热，直接或间接地用于空间加热。这种方式主要被闭式压缩电热泵运用。
45、过程处理的供热和制冷：许多工业需要保持一个4090oC的处理水，并且为了满足洗涤、公共卫生和清洁要求，常有一个即制冷又供热的综合的系统的一部分。这种情况下，主要采用闭式压缩电热泵。但是也有少量的吸收式热泵和热交换器被采用。 蒸汽生产：因为蒸汽被直接用在工业过程中，和用于热分配器，所以工业消耗大量的100200oC的温度范围的低、中和高压蒸汽。当前，高温热泵能生产高达150oC的蒸汽（一个标准的热泵能达到300oC）。在此情况下开式和半开式MVR系统。闭式压缩热泵，串联系统和一些热交换器都可以应用其中。 干燥处理：热泵被广泛应用在低温和适温（最大100oC）的工业蒸馏和干燥过程中。主要的应用有纸
46、浆和纸张的干燥，各种食品生产，木制品和木料。对温度敏感的产品的干燥也有应用。热泵干燥通常能提高干燥产品的质量。因为干燥是在闭式系统中执行的，从干燥食物等中散发的气味大大减少。应用于干燥处理的主要有闭式压缩热泵和MVR系统。 蒸发和蒸馏过程：蒸发和蒸馏是能量集中的过程，因此在化工和食品加工中，大多数热泵被安装在这些过程中。在蒸发过程中，渣滓是主要的产品，而在蒸馏过程中蒸汽是主要的产品。绝大多数系统是开式或半开式MVRs,但是闭式压缩热泵也可以运用其中。低温升使得有630的COPs范围的高性能。2热泵在住宅和商业建筑中的应用1）作用为建筑提供热量和制冷的热泵按照它们的操作原则可以分为以下四种主要的
47、类型： 仅仅供热的热泵，提供热空气和/或者是热水。 既供热又供冷的热泵，既提供热空气又提供冷水。最普通类型的热泵是可逆的空气-空气热泵，它既可以用来供热又能用于制冷。用在商业、政府机关的建筑中的大型热泵采用冷热分配的水循环，因此它们能同时供热和制冷。 混合式热泵，提供热空气、冷水、热水，并且同时重新获得耗尽的热空气。热水可以通过换热器加热，或者通过换热器和冷凝器加热。当只需要热水，不需要热空气和冷水时，可以使用换热器和冷凝器来进行加热。 热泵的的水加热器，充分的对水加热。热泵通常直接从环境中提取空气来作为热源，但是也能作为排气热泵，或者在空气-空气热泵和水-空气热泵的换热器中。在住宅房间的应用
48、中，热泵可以采用可逆的空气-空气热泵（无管或分散式）。热泵也能整体的用于压力-空气管道系统或者屋面供热或散热器（中央系统）。在商业、公共机构建筑中，热泵系统是从一个中央系统连接到空气管道或水系统，或者是一个多区域的系统，复合式的热泵是把热泵单元放置在不同的地方，单独进行空气调节。在大建筑物中用的是水循环热泵系统，它包括一个封闭的水循环，复合式热泵连接到环路中去制冷或制热，和一个冷却塔和一个辅助的热源。热泵在住宅和商业建筑中用到的不同的热源将在热源这一部分介绍。下面这一段介绍用在建筑中的供热，制冷的型式。2）冷热分配系统在日本和美国，热泵已经形成了成熟的市场，而在这成熟的热泵市场中，空气是最普通的交换介质。空气能被直接送入房间或者通过一个压力管道系统。一个空气系统的输出温度通常在30-50oC之间.分水系统主要用在欧洲，加拿大和美国东北部地区。传统的散热器型式的系统要求的高温通常在60-90 oC.现在的低温散热器和对流式散热器设计的最大控制温度在45-55 oC，30-45 oC用在屋面供热。表格1概述了各种冷热分配系统的温度要求。表格 1: 各种冷热分配系统的传热温度.应用温度范围(C)空气分配热空气30 - 50屋面供热
