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1、Heating SystemA steam (heating) system uses the vapor phase of water to supply heat or kinetic energy through a piping system. As a source of heat, steam can heat a conditioned space with suitable terminal heat transfer equipment such as fan coil units, unit heaters, radiators, and convectors (finne
2、d tube or cast iron), or steam can heat through a heat exchanger that supplies hot water or some other heat transfer medium to the terminal units.Water systems that convey heat to or from a conditioned space or process with hot water are frequently called hydronic heating systems. The water flows th
3、rough piping that connects a boiler, water heater to suitable terminal heat transfer units located at the space or process.Classified by flow generation, hydronic heating systems may be (1) gravity systems, which use the difference in density between the supply and return water columns of a circuit
4、or system to circulate water; or (2) forced systems, in which a pump, usually driven by an electric motor, maintains the flow.Cast-iron RadiatorExpansion TankElectric BoilerRelief ValvePumpReturn PipeCold Water FillSupply PipeRadiatorIn the direct-return system, the length of supply and return pipin
5、g through the subcircuits is unequal, which may cause unbalanced flow rates and require careful balancing to provide each subcircuit with design flow. Ideally, the reverse-return system provides nearly equal total lengths for all terminal circuits.Solar Altitude and Solar AzimuthSNormalSolar Altitud
6、eSolar Azimuth(偏东为负,偏西为正) The current value of the solar constant (which is defined as the intensity of solar radiation on a surface normal to the suns rays, just beyond the earths atmosphere at the average earth-sun distance) is 1367 W/m2.060120180240300360132013401360138014001420 太阳辐射强度(W/m2)日序数大气
7、层外太阳辐射强度随日期的变化 03601 0.033 cos365nII0.00.51.01.52.02.53.005001000150020002500 光谱辐射强度(W/m2微米)波长 (微米) 6000K黑体辐射 大气层外太阳辐射 透过大气层的太阳辐射(AM1.5)Spectral Solar Irradiation99 的能量集中在在0.28m到5.0m的波段之间。Direct solar radiationDiffuse solar radiationGlobal solar radiation Global solar radiationDirect solar radiation
8、 Diffuse solar radiationShorter wavelengthHigh proportionLonger wavelengthTemperature increaseGreenhouse effectFive Elements of Passive Solar Home DesignAperture (Collector) The large glass (window) area through which sunlight enters the building. Absorber The hard, darkened surface of the storage e
9、lement. Thermal mass The materials that retain or store the heat produced by sunlight. Distribution The method by which solar heat circulates from the collection and storage points to different areas of the house. Control Roof overhangs can be used to shade the aperture area during summer months.Act
10、ive solar heating system1: Sensor 传感器传感器2: Air Vent 排气口排气口3: Sensor wire 传感器线传感器线4: Pump or circulator 循环泵循环泵5: Pressure Relief Valve 减压阀减压阀6: Sensor 传感器传感器7: Pressure Relief Valve 减压阀减压阀8: Thermometer 温度计温度计9: Tempering Valve 混水阀混水阀 调温阀调温阀10: Hot water output 热水输出热水输出11: Cold water feed line 补水管补水管
11、12: Knob adjusts water temperature output 13: Bypass “H” valve 旁通阀旁通阀14: Check Valve 逆止阀逆止阀15: Solar collectors inlet 太阳能采集器入口太阳能采集器入口16: Pressure Relief Valve 减压阀减压阀17: Collectors & Absorber Plate 太阳能采集器太阳能采集器18: Auxiliary heater 辅助加热器辅助加热器19: Storage Tank 储热罐储热罐20: Differential controller 温差控制
12、器温差控制器21: Pressure gauge 压力表压力表22: Pressure storage tank 储压罐储压罐23: Flowmeter 流量计流量计Solar heating systemsCentral solar heating system with seasonal storage1. Heat Transfer and Fire Tube Boilers Heat Transfer ranks second Fire Tube Boile rs2. Solar Energy The greenhouse principle Basic solar system co
13、mponents Instrumentation Collectors Absorber Plate Heat Storage3. System Controls System controls for heat storage Space Thermostat Temperature Sensors Control Panel Differential ThermostatFrequently used words and phrases:fire tube boilers 火管锅炉火管锅炉 hydronic heating 循环供暖循环供暖secondary heat exchanger
14、二次热交换器二次热交换器insulating effect 绝热效应绝热效应 firebox 燃烧室燃烧室alternate energy sources 替代能源替代能源cloud cover 云量云量 shorter wavelength 短波短波 longer wavelength 长波长波 absorber plate 吸收板吸收板antifreeze 防冻剂防冻剂 pressure storage tank 储压罐储压罐relief valve 排气阀排气阀 fiberglass 玻璃纤维玻璃纤维centrifugal pump 离心泵离心泵 check valve 逆止阀逆止阀th
15、ermostat 温控器温控器 auxiliary heater 辅助加热器辅助加热器control panel 控制台控制台(面板面板) greenhouse 温室温室differential thermostat 差示恒温器差示恒温器ASME 美国机械工程师协会美国机械工程师协会American Society of Mechanical EngineersFrequently used words and phrases:fire tube boilers 火管锅炉火管锅炉 hydronic heating 循环供暖循环供暖secondary heat exchanger 二次热交换器二
16、次热交换器insulating effect 绝热效应绝热效应 firebox 燃烧室燃烧室alternate energy sources 替代能源替代能源cloud cover 云量云量 shorter wavelength 短波短波 longer wavelength 长波长波 absorber plate 吸收板吸收板antifreeze 防冻剂防冻剂 pressure storage tank 储压罐储压罐relief valve 排气阀排气阀 fiberglass 玻璃纤维玻璃纤维centrifugal pump 离心泵离心泵 check valve 逆止阀逆止阀thermosta
17、t 温控器温控器 auxiliary heater 辅助加热器辅助加热器control panel 控制台控制台(面板面板) greenhouse 温室温室differential thermostat 差示恒温器差示恒温器ASME 美国机械工程师协会美国机械工程师协会American Society of Mechanical Engineers2. The transmission or flow of heat ranks in the field of engineering second only to problems involving the strength of mater
18、ials.hydronic heating: 循环供暖循环供暖secondary heat exchanger: 二次热交换器二次热交换器 rank: 按等级排列按等级排列 strength of materials: 材料强度材料强度approach: 方法方法 blind acceptance: 盲目接受盲目接受elementary: 基本的基本的 gross: 显著的显著的 十足的十足的 粗糙的粗糙的 Hydronic heating maintains comfort in the home by circulating hot water to the secondary heat
19、exchanger.3. In their approach to a problem involving heat transfer, their possible blind acceptance of published elementary laws governing heat flow may lead to gross error in the solution.6. The crown sheet and side walls in the firebox provide a maximum amount of radiant heat transfer surface.As
20、noted: 众所周知的众所周知的 insulating: 绝缘的绝缘的 绝热的绝热的 保温的保温的film of stagnant gas: 滞留气体层滞留气体层 cling to: 依附依附crown sheet: 顶板顶板 side wall: 侧壁侧壁firebox: 燃烧室燃烧室 radiant: 辐射的辐射的in the way of heating surface allowances:在受热面可以承受的情况下在受热面可以承受的情况下temperature differential: 温差温差 scrubbed off:去除去除4. As noted, the chief res
21、istance to the free flow of heat from the source to the point of use is the insulating effect of the film of stagnant gas that always tends to cling to a heat transfer surface. 5. For effective heat transfer and all that it means in the way of heating surface allowances, safe temperature differentia
22、ls, economical operation, and life of equipment, the stagnant gas films must be effectively scrubbed off the heating surfaces. 8. Solar energy is the most popular of the many alternate energy sources being discussed today.copper clad: 镀铜的镀铜的 waterside: 水侧的水侧的the most aggressive conditions: 最不利条件最不利条
23、件alternate: 替换的替换的 替代的替代的scarce: 稀少的稀少的 有限的有限的ever-increasing price: 一直在升高的价格一直在升高的价格7. The firing tubes are copper clad on the waterside. Long tube life is positively assured under the most aggressive conditions.9. Solar energy is an alternative that can reduce our dependence on scarce fossil fuels
24、 with their ever-increasing price.11. However, solar energy can vary from season to season, from 2000 Btu to as low as 500 Btu per square foot per day during a period from June to December.deposit: 堆积堆积 积累积累1400BTU/ft2 .day= 15.9MJ/m2.day solar constant I0=1367 W/m2How to translate?cloud cover: 云量云量
25、10. Each day the sun deposits an average of 1400 Btu per square foot of area to the United States;12. Factors such as cloud cover and geographical location affect the total amount of solar energy received. 14. This is possible because ordinary glass can transmit the shorter wavelength, visible parts
26、 of the sunlight while at the same time preventing the passage of the longer wavelength, invisible heat waves.separate from: 除过除过 greenhouse: 温室温室ordinary: 普通的普通的 transmit: 传播传播 传递传递 passage: 通过通过shorter wavelength: 短波短波 longer wavelength: 长波长波assemble: 组装装配组装装配 low concentration: 低密集度低密集度13. Separa
27、te from the more obvious uses of energy from the sun, such as drying food and warming people, the most common direct use of solar energy is in a greenhouse.15. To get the most from solar energy, a system must be assembled to collect the low concentration of solar energy efficiently and store the hea
28、t energy to use at night and on cloudy days.17. This data can be obtained from a pyronometer, a device that measures insolation (energy from the sun) in Btu per square foot per posed: 被提议的被提议的reading: 读数读数 carry away: 带走带走pyronometer: 日射强度计日射强度计 insolation: 日射能量日射能量16. Designing a solar inst
29、allation requires precise information on the amount of solar energy available at the proposed location.18. Heat flow readings can be compared to insolation data to show how efficiently the collector is operation; that is, how much of the available energy is being carried away by the collector system
30、.measurement of diffuse solar radiation The global solar radiation can be divided into two components: 1) diffuse solar radiation, which results from scattering caused by gases in the Earths atmosphere, dispersed water droplets and particulates; 2) direct solar radiation, which havent been scattered
31、. Global solar radiation is the algebraic sum of the two components.19. Most collectors contain an all-copper absorber plate because of the effective heat transfer characteristics of copper.absorber plate: 吸收板吸收板heat transfer characteristics: 传热特性传热特性domestic water: 家庭用水家庭用水conduct: 传导传导copper fluid
32、-carrying piping arrangement: 铜制的液体输送装置铜制的液体输送装置20. As the temperature of the absorber plate increases, solar heat is conducted from the absorber plate through a copper fluid-carrying piping arrangement.21. When this design is used, additional heat exchangers must be used to heat the domestic water
33、and the water used for heating purposes.22. Water is sometimes used as the heat transfer fluid. It should be mixed with antifreeze or an automatic drain-down system to protect the system from freezing during cold weather and when the solar collector system is shut down, such as when the storage medi
34、um has reached the desired temperature and fluid flow through the collectors is stopped.antifreeze: 防冻剂防冻剂 automatic drain-down system: 自动排水系统自动排水系统pressure storage tank: 压力储存罐压力储存罐 relief valve: 减压阀减压阀vent: 放出放出 排出排出, 通风口通风口, 给给开口开口23. A properly sized pressure storage tank should be used or the ta
35、nk should be vented to the atmosphere and fitted with the proper size relief valves.25. The pumps used to circulate the heat transfer fluid are generally low velocity, centrifugal pumps.fiberglass:玻璃纤维玻璃纤维 withstand: 经受住经受住check valve: 逆止阀逆止阀 array: 排列排列 upset: 扰乱扰乱centrifugal pump: 离心泵离心泵26. Check valves are installed between the heat transfer fluid pump and the collector array. They prevent a reversed flow of the fluid through the system, which would
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