探究变风量空调系统及优化设计方案.doc

此文档收集于网络，如有侵权，请联系网站删除探究变风量空调系统的优化设计方案摘要： 变风量系统有很强的动态特性，加之空调系统固有的非线性，使问题的解决变得非常困难。可目前这方面的研究还比较滞后，设计人员在设计时缺少有效的分析计算手段。国内变风量系统的实践正在兴起，迫切需要可行、有效的辅助设计的分析方法。Abstract: the dynamic characteristic of the variable air volume system has a strong, combined with the inherent nonlinear air conditioning system, makes it very difficult to solve the problem. But its still lags behind, at present the research design personnel in the lack of effective means of analysis and calculation in design. Chinese practice of variable air volume system is on the rise, urgently need to be feasible and effective analysis method of aided design.关键词： 变风量 优化设计Keywords: variable air volume optimization design1、引言1, the introduction变风量空调系统于60年代在美国诞生，其基本原理是通过改变送入房间的风量来满足室内变化的负荷。在当今特别提倡节能和舒适性的条件下，变风量空调系统正在逐渐被人们接收并得到应用。Variable air volume air conditioning system in the 60 s was born in the United States, its basic principle is through the change into the room air volume to meet the indoor load change. In todays special advocate energy saving and comfort conditions, variable air volume air conditioning system is gradually been received and applied.变风量空调系统主要有以下几个优点：Variable air volume air conditioning system mainly has the following advantages:* 由于变风量空调系统是通过改变送入房间的风量来适应负荷的变化，而空调系统大部分时间的部分负荷下运行，所以风量的减少带来了风机能耗的降低。* due to variable air volume air conditioning system is by changing the air into the room to adapt to the changing of the load and air-conditioning system running under the partial load of most of the time, so the air flow to reduce brought a fan to reduce energy consumption.* 区别于常规的定风量或风机盘管系统，在每一个系统中的不同朝向房间，它的空调负荷的峰值出现在一天的不同时间，因此变风量空调器的容量不必按全部冷负荷峰值叠加来确定，而只要按某一时间各朝向冷负荷之各的最大值来确定。这样，变风量空调器的冷却能力及风量比定风量可风机盘管系统减少10-20% * 变风量空调系统属于全空气系统，与风机盘管系统相比有明显的好处是冷冻水管与冷凝水管不进入建筑吊顶空间，因而免除了盘管凝水和霉变问题。* the difference between the conventional air volume or fan coil system, different toward the room in every system, its air conditioning load peak appears in the different times of the day, so the capacity of variable air volume air conditioner need not according to the superposition of all the peak cooling load to determine, but as long as according to certain time facing to determine maximum cooling load of each. , variable air volume air conditioner cooling capacity and air fan coil system, the constant air volume can reduce the 10-20% * variable air volume air conditioning system belongs to the whole air system, compared with the fan coil system has obvious benefit is that of frozen water and condensate pipes dont enter buildings ceiling space, thus from the coil condenser water and mildew problem.* 系统的灵活性较好，易于改、扩建，尤其适用于格局多变的建筑。尽管变风量空调系统有其特有的优点，但在实际设计中还是应注意一些问题，以免其带来的一些负面影响，同时，应深入研究和探讨变风量空调系统，进一步优化其设计理念。* system has good flexibility, easy to change and expansion, especially suitable for chequered architecture. Although variable air volume air conditioning system has its unique advantages, but still some problems should be paid attention to in actual design, in order to avoid some of its negative impact, at the same time, should be in-depth study and discussion on variable air volume air conditioning system, further optimize its design concept.2、空调系统2, air conditioning system2.1、变风量空调系统是通过改变进入房间的风量来满足室内变化的负荷，当房间低于设计额定负荷时，系统随之减少送风量，亦即降低了风机的能耗。故变风量系统比较适合多房间且负荷有一定变化的场合，如办公、会议、展厅等；对于象大堂公共空间、影剧院等负荷变化较小的场合，采用变风量系统的意义不大。所以，一般在以变风量空调为主的大厦中。其大堂等公共空间还是以定风量空调系统为好。由于其场合一般都是高大空间。如果采用变风量空调系统，当其变风量变小时，会改变气流组织，影响空调系统的舒适性效果。2.1, the variable air volume air conditioning system is by changing the air into the room to meet the indoor load changes, when the room is lower than the rated load design, system to reduce air output, which reduces the energy consumption of the fan. So it is suitable for variable air volume system more room and load changes have certain occasions, such as office, meeting, exhibition hall, etc.; To load changes, such as lobby, public Spaces, cinema smaller occasions, adopts variable air volume system. So, in general, which is mainly composed of variable air volume air conditioning in the building. The lobby and other public space or with constant air volume air conditioning system for the better. Due to the occasions are generally tall space. If adopts variable air volume air conditioning system, when the air volume change, will change the airflow organization, influence of comfort air conditioning system.2.2、当今国内设计的变风量空调系统，其末端装置以电动节流式压力无关型为主。该末端装置可分为有带风机和不带机两种。带风机的末端装置又可分为带并联风机的末端装置和带串联风机的末端装置，一般选用以后者为主。2.2, the domestic design of variable air volume air conditioning system, the terminal device is given priority to with electric type throttling pressure has nothing to do. The terminal device can be divided into two kinds of, with the fan and not machine. With fan can be divided into the with parallel fan device at the end of the end of the device and end of the belt series fan device, general selection is given priority to with the latter.图1是典型的单风道变风量空调系统。在通常设计的大楼中，将空调平面分成内外两个区，以围护结构退深3-4米的周边区域定为外区。其内中心区域则为内区。对内区而言，其空间需常年冷负荷，而外区在夏、冬季需不同的冷、热空调。由于内区常年供冷，建议采用不带风机的末端装置，其气流组织亦比较容易保证空调舒适性要求。对于外区，则建议采用带风机的末端装置，其出风口设置再加热器。在北方地区，其再加热器以热水盘管为主；而在南方地区，由于其加热量较小，可以考虑利用富裕的夏季电动制冷机组的用电装机容量来设置电加热器。在冬季空调运行中，周边区域的末端装置将一次冷风风量调至最小值（其设定的最小值用来满足将房间的最小新风量），再由末端装置出口处的加热器加热其空调送风。如设计采用无风机的末端装置出口处的加热器热其空调送风。如设计采用无风机的末端装置，则冬季最小送风量将大大低于夏季运行时的额定设计风量，则势必大大降低送风口的出风风速，严重影响周边区域的气流组织。对于一定的外区冬季空调时的再加热量，当风量减少时，则会提高其空调送风温度，同样影响空调的舒适性效果。故外区一般采用带风机的末端装置，则可 完全避免以上两大问题。通过风机的作用，尽管一次风量减少，由于二次回风的补入，保证了送风量，定于设计的额定风量；同时由于送风量的增加，降低了其它调送风温差。另外，由于末端装置内的风机克服了其出风处再加热盘管的压力，从而降低空调器出风所需提供的静馀压。Figure 1 is a typical single duct variable air volume air conditioning system. In normally in the design of the building, plane is divided into two areas, both inside and outside the air conditioning in palisade structure back 3-4 meters in the surrounding area as the outer zone. Its central area is within the area. Internal area is concerned, its space need annual cooling load, and outside area in summer and winter needs different cold and hot air conditioning. Due to the perennial in inner zone and cooling, recommended not to bring a fan device, at the end of the air distribution is also relatively easy to guarantee comfort air conditioning requirements. For the outside area, is recommended to take fan device, at the end of the outlet set heater. In the north, the heater is given priority to with hot water coil; And in the southern region, because of its less heat, can consider to take advantage of the rich summer electricity installed capacity of electric refrigeration unit to set up the electric heater. In winter in the operation of the air conditioning, the surrounding area at the end of the device will be a cold air volume to minimum value (the setting of the minimum to satisfy most small new air volume) of the room, again by the end of the device at the exit of the heater to heat the air conditioning supply air. Such as design USES no fan device at the exit of the heater heat at the end of the air conditioning supply air. If without the fan at the end of the device for the design, then winter minimum supply air will be much less than the summer design air volume, the rating of the runtime is certainly will greatly reduce the wind the wind out of air supply outlet, serious impact on the air distribution of the surrounding area. For a certain area when the winter air conditioning and heat, when the air volume to reduce, will raise the air conditioning supply air temperature, may also influence the comfort of air conditioning effect. So the outer zone usually use with fan device, at the end of can completely avoid the above two problems. Through the role of fan, although a volume reduction, due to the add secondary return air, ensure the delivery, due to the design of the rated air flow; Due to the increase in air output, at the same time reduces the other adjust supply air temperature difference. In addition, due to the terminal device in the fan overcomes the out wind pressure reheat coil, thus reducing static and residual pressure and outlet air required to provide air conditioner.2.3、还有一种设计思路，即内外区全部无风机的末端装置，出口处也不用设置再加热器，而在周边围护结构内侧下方另设立式风机盘管。夏季空调运行时，完全由变风量末端装置提供的送风量来满足内外区的冷负荷要求；冬季空调运行时，内区冷负荷空调仍由该区的变风量末端装置来提供，而外区的热负荷空调则由周边风机盘管来提供，外区的变风量末端装置只提供其所需的新风量。这种设计方法，由于避免了吊顶内设置带风机制末端装置，从而降低了该风机带来的噪声问题，介同时由于周边需另设立式风机盘管，这势必减少了空间的利用率，对室内装修也带来了一定的影响。当然，这种设计方法已不是真正意义上变内量空调系统。2.3, there is a kind of design idea, namely inside and outside the area all have no fans at the end of the device, also dont have to set again heater at the exit, and at the bottom of the inside of the enclosure structure surrounding the establishment type fan coil units. Summer air conditioning operation, complete by the end of the variable air volume device provided by the inner and peripheral zone of air output to meet the cooling load requirements; Winter air conditioner is running, the district cooling load is still consists of the variable air volume air conditioning terminal devices to provide, and outside the thermal load of air conditioning is provided by surrounding fan coil, the outer zone vav terminal device only provides the new air volume required. This kind of design method, as so as to prevent the wind from ceiling set mechanism end device, which reduces the noise problem of the fan, the interface at the same time, due to the surrounding additional set of type fan coil units, this will reduce the utilization of the space, the indoor decoration also brings about certain influence. Of course, this design method has been not in variable volume air conditioning system in real sense.3、空气处理3, air treatment图2是典型的变风量空调系统冬季运行时的空气状态变化图，系统设计中，各楼层的一次风空调器只设冷却盘管，而集中式新风空调器设置冬季预热盘管和加湿器。作为冬季运行，新风经新风空调的预热盘管加热至O1或O2点，经加湿处理后至E点，而后与楼层空调回风混合后达到R点，再经一次风空调器的冷却盘管处理至出风状态点S.新风加器可以采用等温加湿和绝热加湿两种方法。由于新风加湿量较大，故等温加湿一般采用乾饱和蒸汽加湿法，而绝热加湿法，对于高压叶喷雾加湿法，由于无法做到比例调节，实际运行时控制精度很差，故新风加湿一般以采用乾饱和蒸汽等温加湿为主。该空调系统夏季运行时，新风空调器不作任何处理过程由楼层空调器各自承担，其空气处理过程如图3所示。这种设计方法的优点是，所有楼层空调器只设冷却盘管，而由新风空调器集中处理冬季室外新风的加热和加湿过程。这样，简化了整个大楼的空调系统，也大大节约了系统的初投资费用。但其缺点是，为了室内新风的集中加湿，必需先对其等湿加热，而楼层空调器对其混风空气进行冷却处理才能达到空调所需的一次风出风状态点。如此空气处理过程，势必产生空气先加热扣冷却的抵消作用，造成大楼空调系统运行时能耗的大量浪费。Figure 2 is a typical variable air volume air conditioning system air condition variation in running in winter, in system design, each floor a wind of air conditioner cooling coil, only the centralized air conditioner set winter preheating coil and humidifier. As winter running behavior by the outdoor air preheating heating coil to O1 and O2 point, after humidifying treatment to point E, after before mixed with return air floor air conditioning to achieve rumet point, then through a wind of air conditioner cooling coil processing to the state of wind point s. fresh adder isothermal humidifying and adiabatic humidification can be used two ways. Due to large quantity of fresh air humidification, the isothermal humidifying generally dry saturated steam humidifying method is adopted, and the adiabatic humidification method, for high-pressure spray humidification method, because it could not achieve proportional control, the actual runtime control accuracy is very poor, so the air humidification general mainly adopts dry saturated steam isothermal humidification. The operation of the air conditioning system in summer, air conditioner do not make any processing shall be borne by the respective floor air conditioner, air handling process is shown in figure 3. This design method has the advantage that all floor air conditioner cooling coil, the air conditioner will focus on the winter heating and humidification process of outdoor air. So, simplifies the whole building air conditioning system, also greatly save the initial investment cost of the system. But its disadvantage is that, for the sake of the concentration of indoor air humidification, must wait for its first wet heat, and the floor air conditioner mix the wind to its air cooling processing to achieve a required for air conditioning wind the wind state points at a time. So the air handling process, it is bound to produce air heating cooling of offset function, the first building air conditioning system operation energy consumption caused by a large number of waste.针对上述空调系统的缺点，笔者建议集中式新风空调器只设预热盘管，不设加湿器。大楼标准层的空调器只设冷却盘管和高压喷雾加湿器，而对于其它楼层有额定热负荷的情况下再加设加热盘管。该空调系统夏季运行时，其空气处理过程也如图3所示。而作为冬季运行，新风空调器只对室外新风进行预加热，新回风混合后进入楼层空调器，空调器则根据控制要求对其加热或冷却（对于不同楼层，回热或冷却可能同时存在）当然，新风加热处理后温度设定值的前提是大于+5C，且保证标准层空调器的入风空气状态R2的焓值不低于S点，避免其加热过程。经盘管后的空气状态点，其空气处理过程如图4所示。该变风量空调系统，由于充分利用了冬季室外新风集中加湿而产生的大量冷热抵消作用，是一种比较节能的空调形式。Faults in the air conditioning systems, the author suggested that the centralized air conditioner preheating coil only. Do not set the humidifier. Building standard layer of air conditioner cooling coil pipe and high-pressure atomizing humidifier, only for the other floors are rated heat load cases and added a heating coil. The operation of the air conditioning system in summer, the air handling process is as shown in figure 3. In winter operation, air conditioner only for fresh air preheating, the new return air mixture into the floor air conditioner, air conditioner, according to the requirements of control on the heating or cooling (for different floors, heat or cooling may exist), of course, fresh after the heat treatment temperature set point is the premise of greater than + 5 C, and guarantee the standard layer air conditioner state of wind into the air enthalpy value of R2 is not lower than S points, avoid the heating process. After the coil of the air condition, the air handling process as shown in figure 4. The variable air volume air conditioning system, due to take full advantage of the concentration of winter outdoor air humidification and produce large amounts of hot and cold offset function, is a energy-saving air conditioning form.4、冷热源4, cold and heat source对于变风量空调系统，冬季和过渡季节运行时需同时满足内外区的冷、热负荷要求，故空调水系统采用四管制。由于系统要求同时提供冷、热源，除采用常规的电动制冷机组加蒸汽或热水锅炉外，可以考虑采用直燃式溴化锂冷热不机组，其具有运转时无振动，无磨损，运行经济可靠等优点。不过，如采用直燃机组需注意以下几个问题：For variable air volume air conditioning system, in winter and transition seasons runtime needs to satisfy both inside and outside the cold, heat load requirement, so the air conditioning water system consists of four controls. Due to the system requirements at the same time provide cold and heat source, in addition to the use of the conventional electric refrigeration unit and steam or hot water boiler, consider using direct-fired lithium bromide cold heat is not set, it has operation, no vibration, no wear, economic and reliable operation, etc. However, if use direct combustion unit should pay attention to the following questions:* 机组供水温度 因为溴化锂机组的冷冻水供水温一般只能达到+7C左右，当变风量空调系统设计低温系统时，系统需提供足够低温的冷冻水，而这对于溴化锂组而言就难以胜任了。* unit water supply chilled water temperature for lithium bromide units for water temperature can reach + 7 C or so commonly, when a variable air volume air conditioning system design of the system of low temperature and system needs to provide enough low temperature of chilled water, and that it would be difficult to competent for lithium bromide group.* 直燃机组需采用分隔式供热机组 如果采用主体供热式直燃机组，由于无法同时制冷和制热，不能满足变风量空调系统需同时提供冷、热源的要求。* direct combustion units should use space type heating units if the main body heating type, direct combustion unit due to cooling and heating at the same time, cant satisfy the variable air volume air conditioning system, cold/heat source requirements shall be supplied at the same time.* 配置低负荷运行时只有内区少量冷负荷，其总冷负荷大大低于夏季空调时的总负荷，如在此低负荷情况下运行，直燃机组将大大降低其运行的经济性和可靠性。故此时，低负荷制冷由独立的电动冷水机组承担为好，直燃机组只作制热用。* configuration when only a small amount of cooling load in inner zone of operation under low load, the total cooling load is much lower than the total load of air conditioning in summer, such as the low load running, direct combustion unit will greatly reduce the efficiency and reliability of its operation. Therefore, low cooling load borne by independent electric chiller for good, only direct combustion unit for heating.在空调水系统设计中，冷却塔可以设计采用独立小塔不分彼此、统一组合的形式，所有冷却塔风机采用双速风机。实现运行时，不管入塔水量及水温如何变化，冷却塔通过调节风机风量以保证出塔却水的温度，这样可以有效降低冷却塔的运行能耗。由于变风量空调系统冬季亦需提供冷源，可考虑在室外空气条件允许的情况下，利用冷却塔的冷却能力，通过板式热交换器，提供一定低温的冷冻水，以达到不开冷水机能的节能空调运行。In the design of air conditioning water system, cooling tower can be designed using independent small tower regardless of each other, combination in the form of unity, all adopt double-speed fan cooling tower fan. Implementation is run, no matter how into the water tower and water temperature changes, the cooling tower by adjusting the fan air volume to ensure that the tower is the temperature of the water, it can effectively reduce energy consumption of the operation of the cooling tower. Because variable air volume air conditioning system also must provide cold source in winter, can consider in the case of outdoor air conditions allow, using the cooling capacity of cooling tower, through the plate heat exchanger, provide a low temperature of chilled water, in order to achieve the function of energy saving air conditioning dont open cold water running.5、风量平衡5, air volume balance图5是典型的变风量系统的经济运行。对于采用混风的空调系统，新风量在各个房间是按风量分配的。也就是说，即使总新风量达到要求，在的房音也会有新风不足的问题，对于变风量系统，由于送入房间的要求，总新风量将会增加，基至在有的时候可能超过空调需要的送风量。为此可这样考虑，在一定的新风量下，总回风中二氧化碳的含量不一定超标，可以利用回风以减少总新风量。图示空调系统运行时，送风机根据空调负荷确定送风量，新风机则根据回风的空气品质确定提供的新风量，而排风机则根据房间的所需正压值匹配新风机的运转。在过渡季节，调节新风机和排风机的运转风量来维持一定的新回风混风温度，这样做法是充利用室外新风的低湿冷却作用以减少冷机的开启时间。但在实际采用时，如大楼标准层独立设置一套变风量空调时间。但在实际采用时，如大楼标准层独立设置一套变风量空调系统，这种做法需在每个楼层设两台变频调速风机（新风机和排风机）。这势必增加了每个空调机房所占的空间，也大大增加了初投资费用。为保证室内空气品质，系统实际运行时，是通过探测回风空气中的CO2浓度来控制新风量的，但CO2浓度达到要求并不能代表室内建筑空气品质合格，室内还会存大其它挥发性污染物。Figure 5 is a typical variable air volume system economic operation. Mix the wind is used for air conditioning system, the new air volume is according to the air distribution in each room. That is to say, even if the total has met the requirement of the new air volume, also in the room will have the problem of insufficient fresh air, the variable air volume system, due to the requirement into the room, a total new air volume will be increased, and in some time may be more than