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。本文针对办公建筑空调设备的节能问题，提出了一种新的空调系统，既减少了空调器的热传输能耗，又实现了舒适的室内环境。该系统的特点进行了描述。建议的空调系统重视自然通风盘管的天花板。与风扇输送空气相反，这些是冷却盘管，通过室内温差引起的自然对流循环空气来降低室温。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量。结果表明，与传统系统相比，将自然通风盘管安装在天花板上的系统可以减少25 ~ 30%的年耗电量。此外，在小型实验室中进行了实验，研究了使自然通风盘管的制冷能力最大化时的制冷特性。具体而言，我们研究了天花板开口面积，烟囱效应的盘管下的网格长度，和天花板集气室的长度对冷却能力的影响。最后，利用本实验的结果，我们进行了模拟，以澄清自然通风盘管的冷却特性。

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.