关于暖通空调系统的节能问题
随着经济的迅速发展,能源和环境问题日益尖锐。在特别炎热的夏天,我们都切身地体会到了电力的紧张。可以预见,这种状况在今后还会出现,并且会日趋严重。
1、暖通空调领域节能的重要性和可行性
随着社会的发展,建筑能耗在总能耗中所占的比例越来越大,在发达国家已达到40%,据统计在湖南省也达到27.8%。在城市远高于这个比例。而在建筑能耗里,用于暖通空调的能耗又占建筑能耗的30%-50%,且在逐年上升。随着人均建筑面积的不断增大,暖通空调系统的广泛应用,用于暖通空调系统的能耗将进一步增大。这势必会使能源供求矛盾的进一步激化。另一方面,现有的暖通空调系统所使用的能源基本上是高品位的不可再生能源,其中电能占了绝对比例。对这些能源的大量使用,使得地球资源日益匮乏,同时也带来严重的环境问题,如在我国的一些地区酸雨、飘尘问题呈日益严重之势,对生态环境和可持续发展带来了很大影响。以湖南长沙地区为例,2003年夏季电力系统最大负荷大约为160万千瓦,据有关部门推算,其中空调系统的负荷就占了约60万千瓦。在最热的夏天,如果对暖通空调系统采取节能措施,不仅可以大大缓解电力紧张状况,同时对于降低不可再生能源的消耗、保护生态环境、维持可持续发展、振兴湖南经济等都有着重要的意义。根据暖通空调行业的研究成果,现有空调系统的能耗是惊人的,如果采用节能技术,现有空调系统节能20%-50%完全可能。显然,如果对长沙地区的空调系统和建筑系统采用节能措施,那么即使遇到今夏那样的炎热天气,长沙也不会超过现有电力系统峰值而停电了。
2、暖通空调领域节能的途径与方法
科学技术的不断进步,使暖通空调领域新的技术不断出现,我们可以通过多种方法实现暖通空调系统的节能。
2.1、精心设计暖通空调系统,使其在高效经济的状况下运行
暖通空调系统特别是中央空调系统是一个庞大复杂的系统,系统设计的优劣直接影响到系统的使用性能。例如系统往往都是按最大负荷设计的,而实际运行
基本上是在部分负荷下运行,如果系统各部分的设计不能满足部分负荷运行的要求,那系统的能耗是很大的。又如新风系统的设计,系统应该能随着室外气象参数的变化改变新风量,以最大限度地缩短主机的开启时间。可以说空调系统的设计对系统的节能起着重要的作用。
2.2、 改善建筑维护结构的保温性能,减少冷热损失
我们知道对于暖通空调系统而言,通过维护结构的空调负荷占有很大比例,而维护结构的保温性能决定维护结构综合传热系数的大小,亦即决定通过维护结构的空调负荷的大小。所以在国家出台的建筑节能设计规范和标准中,首先要求的就是提高维护结构的保温隔热性能。
2.3、提高系统控制水平,调整室内热湿环境参数,尽可能降低空调系统能耗 空调系统特别是舒适性空调系统对人体的作用是通过空气温度、湿度、风速、环境平均辐射温度进行的,人体对环境的冷热感觉是这些环境因素综合作用的结果。以往的空调控制方式仅仅是测控空气的温度湿度,甚至仅空气温度。显然是不全面的,势必带来许多问题,如空调系统对人体的作用不直接、当环境变化时对环境的调控不迅速、人体感到不舒适、空调系统的这种调控方式不节能。热湿环境研究成果的应用,为我们采用新的控制方式方法提供了理论基础。如果采用舒适性评价指标即体感指标作为空调系统的调控参数,如采用PMV或SET*指标对空调系统进行调控,不仅可以解决传统控制方法存在的弊病,而且可以实现大幅度的节能,据我们的初步研究表明,采用这种控制方法可使空调系统在人体舒适的条件下节能30%左右。
2.4、采用新型节能舒适健康的空调方式
如上所述,影响人体热舒适性的环境参数众多,不同的环境参数组合可以得到相同的热舒适性效果,但不同的热湿环境参数组合空调系统的能耗是不相同的。例如在冬季,如果我们采用传统的空调方式,把整个室内的空气加热,通过空气实现人体与环境的热湿交换,就需要较高的空气温度,此时通过维护结构的热损失和加热新风的热损失都比较大。如果我们根据热湿环境的研究成果,改变传统的空调方式,增加辐射热(如低温地板辐射采暖),此时所需要的空气温度降显著下降,一般可达到12~14度,而传统方式一般在18~20度,显然后者比前者具有显著的节能效果。在夏季也有类似的结果。 2.5 推广应用使用可再生能源或
低品位能源的空调系统
随着空调系统的广泛应用,空调对不可再生能源的消耗将大幅度上升,同时对生态环境的破坏也在日趋加剧。如何利用可再生能源及低品位能源已经成了该领域重要的研究课题。地源热泵空调系统就是在这种形势下发展起来的,它利用地下恒温层土壤热显著提高空调系统的COP值,使得同等制热(或制冷)量下的系统能耗大幅度下降。另外,利用太阳能供热或制冷技术也在开发研究着。 2.6、开展冷热回收利用的研究运用工作,实现能源的最大限度利用 目前许多空调系统冷热回收利用研究也在蓬勃开展,如空调系统排风的全热回收器,夏季利用冷凝热的卫生热水供应等,都是对系统冷热的回收利用,显著提高了空调系统能源利用率。
3、存在的问题与对策
要实现空调系统的节能降耗,已经具备了许多成熟的条件,但同时也存在许多问题有待于解决:
3.1、暖通空调系统的设计管理问题
如前所述,空调系统的设计对空调系统的节能性有着重要的影响。然而在实际中往往得不到一些设计部门和设计人员的足够重视,使得设计建造的系统不仅初投资大,运行能耗也相当惊人,大大超过了国家标准。据实测,有的公共建筑的空调能耗占建筑总能耗的60%。为此, 我们有必要建议政府有关职能部门加强对暖通空调设计项目的管理,可以委托相关部门学会对设计图纸进行严格审查,对未达到国家有关节能标准的设计严禁修建。 3.2、暖通空调系统的运行管理问题
除设计外,我们发现运行管理也起着重要的作用。有些单位的空调系统,一年四季只有开机关机和冬夏季转换操作,显然系统达不到相应的节能效果。为此要求运行管理人员不仅要有强烈的责任心,上岗前还必须要进行系统的培训和考核,对没有达到要求的,应重新培训,考核合格后才能上岗。在调查中我们发现,同样一套系统,管理人员不同,系统的能耗大不相同,有的甚至相差50%以上。 3.3、新型空调方式、控制方法及新的节能技术的开发应用问题
如前所述,采用新型空调方式、新的控制方法,不仅能显著提高热舒适性而且可以使系统大幅度节能。在我省对新型空调方式和控制方法的研究可以说在全国
都是比较早的,并且已经取得了一些可喜的成果,只要政府部门略加扶持这些成果将很快能得到适用,并形成产业化,对这些项目的实施,将对我省的能源、环境和经济都将起到巨大的推动作用。
3.4、公众对空调系统作用的理解观念问题
对于舒适性空调系统,从本专业的角度来讲就是使人体有好的热舒适性。而在社会上我们常常发现一种这样的观念:认为空调在夏季是越冷冬季越热效果越好。这显然与舒适性空调的出发点相违背的。事实上,这样不仅大大增大了空调系统的能耗,同时由于室内外温差的增大,也使人体对不同环境的适应性下降,身体免疫力降低。这些可以通过宣传改变人们的观念。 3.5、使用可再生能源空调系统的开发推广应用问题
利用可再生能源的暖通空调系统,如地源热泵空调系统、太阳能制冷、供热系统,不仅有着显著的环境和社会效益,有的还有着显著的经济效益(如地源热泵空调系统),应大力开发推广。当然,和其他任何新技术一样,这些技术也存在着一些问题(如地源热泵系统的地源热提取问题等),也需要进一步研究完善,也需要政府部门的重视和支持。
综上所述,暖通空调系统在建筑节能中占据重要的位置,起着重要的作用,节能技术的研究开发和运用是暖通空调系统、建筑系统节能的基础,政府职能部门的重视和支持,则是实现大幅度节能、产生显著的环境和社会效益、推动经济发展的保证。
英文
On the Issue of Energy Saving HVAC Systems
With the rapid economic development, energy and environmental issues become increasingly acute. In especially hot summer, we all appreciate the vital tension electricity. It is foreseeable that this situation will arise in the future and will become increasingly serious. 1.An energy-saving HVAC field the importance and feasibility of
With the social development, building energy consumption in the proportion of total energy consumption increasing in developed countries has reached 40%, according to statistics in the Hunan province has reached 27.8%. Much higher than the percentage in the city. In building energy consumption, the energy consumption for air conditioning in another building 30% -50% energy, and in the year by year. With the continuous increase of per capita floor space, the extensive application of HVAC systems for the energy consumption of HVAC systems will be further increased. This contradiction between energy supply and demand will inevitably lead to further intensification. On the other hand, the existing HVAC system energy use is basically a high-grade non-renewable energy, which accounts for the absolute power ratio. On these large-scale use of energy, increasing scarcity of the Earth, and also cause serious environmental, for example, in our country of acid rain, airborne dust was growing potential issues, on the ecological environment and sustainable development has brought great impact. Case Study of Changsha in Hunan, the summer of 2003 peak load power system is about 1.6 million kilowatts, according to authorities estimated that the load on air conditioning system which accounted for about 60 million kilowatts. In the hottest summer, if HVAC systems energy-saving measures, not only can greatly ease the power strain state, meanwhile towards reducing non-renewable energy consumption, protect the environment and maintain sustainable development, revitalizing the economy and so has an important Hunan significance. HVAC industry, according to research results, the energy consumption of existing air conditioning system is amazing, if we adopt energy saving technology, the existing air conditioning system efficiency of 20% -50% is possible. Obviously, if the air conditioning system in Changsha and building systems using energy-saving measures, then even in the face this summer as the hot weather, Changsha will not exceed the current peak power systems and electricity was cut off.
2 .HVAC field ways and means of energy conservation
Science and technology advances, so HVAC emerging field of new technologies, a number of ways
we can achieve energy saving HVAC systems.
2.1 HVAC system is designed so that the economic situation in the efficient running
HVAC system, particularly the central air conditioning system is a large and complex systems,
system design will directly affect the system performance. Such systems are often designed by the maximum load, while the actual operation is basically the part load operation, if the system part of the design can not meet the requirements of part load operation, then the system's energy consumption is significant. Another example is the design of the new air system, the system should be able to change with changes in outdoor fresh air meteorological parameters in order to shorten the maximum time the host of the opening. Can be said that the system air-conditioning system design plays an important role in energy conservation.
2.2 improve the insulating performance of building maintenance to reduce the loss of hot and cold
We know that the HVAC systems, air conditioning load by maintaining the structure of a large proportion, while maintaining the insulating performance of the decision to maintain the size structure of complex heat transfer coefficient, which determine the structure of the air conditioning load by maintaining the size. Therefore, state policies and standards for building energy efficiency design, the first requirement is to increase the thermal insulation properties to maintain the structure.
2.3 Improve the system control level, adjust the indoor thermal environment parameters, to minimize energy consumption of air-conditioning system
Comfort air conditioning system, particularly the role of air-conditioning system on the human body
through the air temperature, humidity, wind speed, the average radiation temperature of the environment, and human feeling hot and cold on the environment of these environmental factors combined result. Before air-conditioning control method is only monitoring the temperature of the air humidity, air temperature, even only. Is obviously not comprehensive, is bound to bring many problems, such as the role of air-conditioning system on the human body does not directly, when the environment changes, the regulation on the environment is not rapid, the body does not feel comfortable, air-conditioning systems that control methods are not saving. Thermal environment of the application of research results, as we approach a new control method provides a theoretical basis. If that is a comfort evaluation index of somatosensory indicators as air-conditioning system control parameters, such as the use of PMV or SET * index of the air conditioning system to control, not only can solve the shortcomings of traditional control methods exist, and can achieve significant energy conservation, according to our Preliminary research shows that using this control method can make the air conditioning system in the human comfort conditions save 30%.
2.4 The use of new energy-saving air conditioning comfortable and healthy
As noted above, affect human thermal comfort environment of many parameters, different
environmental parameters can be the same thermal comfort effect, but different thermal environment parameters for energy consumption air conditioning system is not the same. For example, in the winter, if we use a traditional air conditioning, heating the entire indoor air through the air to achieve the body heat and moisture exchange with the environment, we need a higher air temperature, then heat loss by maintaining the structure and heating fresh air greater than heat loss. If we follow the thermal environment of research results, changing the way traditional air-conditioning, increased radiant heat (such as low temperature radiant floor heating), then the need to lower the air temperature dropped significantly, and can be reached from 12 to 14 degrees, while the traditional general 18 to 20 degrees, obviously the latter than the former has significant energy savings. In the summer, a similar result. 2.5 promote the use of renewable energy or low-grade energy, air-conditioning systems
With the extensive use of air-conditioning system, air conditioning on non-renewable energy consumption will be greatly increased, while the destruction of the ecological environment are becoming increasingly intensified. The use of renewable energy and low grade energy has become an important research topic in the field. Ground source heat pump system is developed in such a situation, it makes underground layer of soil temperature significantly improved thermal COP value of air-conditioning system, making the same heating (or cooling) energy consumption under capacity significantly. In addition, the use of solar energy heating or cooling of the technology is also developing.
2.6 The research carried out using cold and hot recycling work to achieve maximum use of energy
At present, many recycling of hot and cold air-conditioning systems have also been carried out, such
as full air conditioning exhaust heat recovery system, hot summer, the health advantage of condensing hot water supply are all hot and cold recycling system, significantly improved the air-conditioning system energy efficiency. 3 Problems and Solutions
To achieve energy saving air conditioning system, already has a number of mature conditions, but also many problems to be solved:
3.I HVAC system design and management issues
As mentioned earlier, the design of air-conditioning system energy saving air-conditioning system has an important effect. However, in practice, often without some of the design department and design staff adequate attention, making design and construction of the system is not only a large initial investment, energy consumption is quite amazing, greatly exceeding the national standard. It is measured, and some public buildings, the air conditioning energy consumption accounts for 60% of total energy consumption of buildings. To this end, we need to suggest that the relevant functional departments to strengthen the management of HVAC design project, commissioned by the relevant departments can learn rigorous review of design drawings, for failure to meet the national standards for the design of energy-saving construction is prohibited. 3.2 HVAC system operation management
In addition to the design, we found that operation and management also play an important role. Some units of the air-conditioning system throughout the year only the start of winter and summer shutdown and conversion operations, the system is clearly not meet the appropriate energy-saving effect. Have requested the operation and management staff must not only have a strong sense of responsibility must be to conduct pre-job training and assessment system, and did not meet the requirements, should be re-training and passing the examination before appointment. In the survey we found that the same set of systems, managers of different, very different systems of energy, or even a difference of 50%.
3.3 The new air conditioning, control methods and the development of new energy-efficient application of technology
As mentioned above, using new air conditioning system, new control methods, not only can significantly improve the thermal comfort and energy efficiency can make the system significantly. New type of air conditioning in our province and the control method can be said that in the country are relatively early, and have some encouraging results, as long as the government support of these results will be slightly very soon been observed and the formation of, on the implementation of these projects, will be our province's energy, the environment and the economy will play a huge role in promoting. 3.4 The role of public understanding of the concept of air-conditioning system problems For the comfort of air conditioning system, from the professional point of view is to make the human body has good thermal comfort. In society, we often find a kind of this idea: that the air conditioning in the summer, cold winter, the more heat the more the better. This is obviously the starting point of comfort air conditioning contrary. In fact, this not only greatly increases the energy consumption of air conditioning system, and because the increase of indoor and outdoor temperature difference, but also the body's adaptability to different environmental decline, lowering the body immunity. These can change people's idea of publicity.
3.5 Use of renewable energy development and promotion of application of air conditioning system problems
Use of renewable energy HVAC systems, such as ground source heat pump systems, solar
refrigeration, heating system, not only has significant environmental and social benefits, some also are significant economic benefits (such as ground source heat pump system), should vigorously promote development. Of course, any other new technologies, these technologies there are some issues (such as ground source heat pump system, ground source heat extraction and so on), also require further study and improve the government also needs attention and support departments.
In summary, energy-saving HVAC systems in buildings occupy an important position, plays an important role in energy technology research and development and application of a HVAC system, energy efficient building systems based on functional departments of the government's attention and support , it is to achieve substantial energy saving, resulting in significant environmental and social benefits, ensure the promotion of economic development.
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