Study on high efficiency air-conditioning system with cooling coils for natural convection

建筑领域的节能不仅有助于节约能源，而且有助于遏制全球变暖。针对办公建筑空调设施的节能问题，提出了一种既能降低空调热量消耗，又能营造舒适的室内环境的新型空调系统。描述了该系统的特点，建议的空调系统将自然通风盘管安装在天花板上。与风扇输送空气不同，这些冷却盘管通过室内温差引起的自然对流循环空气，从而降低室内温度。这使得降低输送系统的能耗成为可能。首先，为了评估该空调系统的可行性，我们比较了四种空调系统的年运行能耗。研究发现，将自然通风盘管连接到天花板上的系统与传统系统相比，每年可以减少25%~30%的功率。我们还在小型实验室中进行了实验，研究了自然通风盘管冷却能力最大化时的冷却特性。具体地说，我们考察了天花板开孔面积、烟囱效应下盘管下格栅的长度以及天花板正压送风系统的长度对制冷能力的影响。最后，利用实验结果，对自然通风盘管的冷却特性进行了数值模拟。

Energy conservation in the construction field not only helps to conserve energy resources but also serves to check global warming. This paper focuses on conserving energy in air conditioning facilities used in office buildings, and proposes a new air conditioning system that both decreases the amount of energy consumed for heat conveyance in air conditioners-and achieves a pleasant room environment. The characteristics of this system are described.The proposed air-conditioning system attaches natural-draft coils to the ceiling. As opposed to conveying air by fans, these are cooling coils that lower room temperature by circulating air through natural convection caused by indoor temperature differences. This makes is possible to reduce the amount of energy consumed by the conveyance system.First, to evaluate the feasibility of this air conditioning system, we compared annual operation energy of four air conditioning systems. It was found that a system that attaches natural-draft coils to the ceiling as proposed could decrease annual power by 25 to 30% compared with conventional systems.We also performed an experiment in a small-scale laboratory to study cooling characteristics when maximizing the cooling ability of natural-draft coils. Specifically, we examined the effects of ceiling aperture area, length of grid under coils for chimney effect, and length of ceiling plenum on cooling ability. Finally, using the results of this experiment, we performed simulations to clarify the cooling characteristics of natural-draft coils.