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Experimental investigation of heat leakage and air leakage in domestic refrigerators.

机译：家用冰箱散热和漏气的实验研究。

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摘要

The optimization of the energy consumption in household refrigerators should consider the influence of the gasket which determines the heat transfer and air infiltration rate. In this research project, engineering methods are developed to evaluate the heat leakage due to the gasket and air infiltration in domestic refrigerators.;In the first study, experimental and numerical approaches are applied to evaluate the gasket heat transfer based on the "Reverse Heat Load Method". The main objective is to find the effective heat leakage with the dimensions of energy leakage per gasket length per temperature difference (W/m.K). An insulated cubic box with a 216,000 cm 3 interior enclosure (60cm x 60cm x 60cm) was designed to accept a matching set of adjoining refrigerator door and wall cuts placed inside the cavity. The door and walls are surrounded by thick insulation material so that only the gasket region is exposed to the ambient environment. A heat source was placed inside the center of the box to create a desired temperature difference between the interior and the ambient. Thermocouples measured the interior and ambient temperatures while six heat flux sensors, mounted on the exposed gasket region, measured the heat flux exiting the box through this region. Two restrictions were imposed with the heat flux sensors to evaluate the heat leakage purely experimentally. The heat flux sensors did not offer sufficient resolution to fully resolve the surface heat flux distribution, and they were incapable of directly measuring the heat flux leaving through the gasket due to its complex geometry. Therefore, Computational Fluid Dynamics (CFD) simulations were necessary to complete the heat flux profile between the experimental data points recorded by the sensor). Accordingly, a two dimensional (2D) simulation was performed to provide a shape profile of the heat flux leaving the gasket region which may be used to fit the experimental data using a "Least Mean Square Error" approach. The estimated heat loss at the gasket region with the original gasket installed on the sample refrigerator was 0.20 W/m.K. Extensive testing with other gaskets showed that their design and materials influenced the heat loss of the refrigerator.;The second study developed a methodology to identify the leaks, to estimate the air infiltration rate, and to calculate the energy loss associated with air leaks in domestic refrigerators. The water drain tube was determined to be the primary air leak source due to the presence of the evaporator fan inside the freezer compartment. In addition, many other leaks with unknown sizes were found through bubble tests about the cabinet. Two identical refrigerators were employed to evaluate the impact of the air loads. One refrigerator remained with its original conditions and the other unit was completely sealed so that there existed a single inlet (water drain tube) and a single outlet (a drilled hole). The intact refrigerator was used to measure the normal operating conditions with respect to the ambient environment (e.g. pressure and temperature differences) to mimic these conditions in the sealed unit. The sealed unit had a hole drilled into the cabinet and the water drain tube remained open to the ambient. The size of the drilled hole was adjusted until the same pressure difference was achieved on the new unit at the same temperature difference. A flow meter measured the air flow through the hole and thermocouples measured the ambient and interior temperatures simultaneously. The energy leakage due to the air infiltration was calculated using the first law of thermodynamics based on two temperatures and mass flow rates at the inlet and outlet. The actual air infiltration rate was measured and the effective heat transfer rate due to the air infiltration rate was calculated 4.4 Watts. Modeling shows that refrigerators are not under steady state operation. They "breathe" drawing air in during cooling and forcing air out during warming between compressor cycles. A hypothetical perfectly sealed unit is shown to produce forces upwards of 350 lbf on the fresh food door due to this effect alone.
机译：家用冰箱的能耗优化应考虑垫片的影响，该垫片决定了传热和空气渗透率。在该研究项目中，开发了工程方法来评估由于家用冰箱的垫片和空气渗透引起的热泄漏。；在第一项研究中，基于“反向热负荷”，采用实验和数值方法来评估垫片的传热。方法”。主要目的是找到有效的热泄漏量，以及每垫片长度每温差（W / m.K）的能量泄漏量。一个带有216,000 cm 3内箱（60cm x 60cm x 60cm）的隔热立方盒被设计成可以接受一组匹配的相邻冰箱门和放置在空腔内的墙壁切口。门和墙壁被厚厚的绝缘材料包围，因此只有垫圈区域暴露在周围环境中。将热源放置在盒子的内部，以在内部和环境之间产生所需的温差。热电偶测量内部和环境温度，而安装在裸露垫圈区域上的六个热通量传感器则测量通过该区域从盒子中流出的热通量。对热通量传感器施加了两个限制，以纯粹通过实验评估热泄漏。热通量传感器无法提供足够的分辨率来完全解决表面热通量分布问题，并且由于其复杂的几何形状，因此无法直接测量通过垫圈的热通量。因此，计算流体动力学（CFD）模拟对于完成传感器记录的实验数据点之间的热通量分布十分必要。因此，进行了二维（2D）仿真以提供离开垫片区域的热通量的形状轮廓，该形状轮廓可用于使用“最小均方误差”方法来拟合实验数据。在样品冰箱上安装了原始垫圈的情况下，在垫圈区域的估计热损失为0.20 W / m.K。对其他垫圈的广泛测试表明，其垫圈的设计和材料会影响冰箱的热损失。；第二项研究开发了一种方法来识别泄漏，估算空气渗透率并计算与家用空气泄漏相关的能量损失冰箱。由于冷冻室内部存在蒸发器风扇，排水管被确定为主要的空气泄漏源。此外，通过对机柜进行的气泡测试还发现了许多其他未知尺寸的泄漏。使用两个相同的冰箱来评估空气负荷的影响。一台冰箱保持其原始状态，另一台冰箱完全密封，因此只有一个入口（排水管）和一个出口（一个钻孔）。完整冰箱用于测量相对于周围环境的正常运行条件（例如压力和温度差），以模拟密封单元中的这些条件。密封装置在机柜上钻了一个孔，排水管对周围保持开放状态。调节钻孔的大小，直到在相同的温度差下在新设备上获得相同的压力差为止。流量计测量通过孔的气流，热电偶同时测量环境温度和内部温度。根据入口和出口的两个温度和质量流率，使用热力学第一定律计算了由于空气渗透而引起的能量泄漏。测量实际的空气渗透率，并计算出由于空气渗透率而产生的有效传热率4.4瓦。建模表明，冰箱不在稳定状态下运行。它们“呼吸”在冷却期间将空气吸入，并在压缩机循环之间的加热期间将空气排出。假设一个完全密封的装置仅由于这种作用就可以在新鲜食品门上产生350 lbf以上的力。

著录项

  • 作者

    Shoai Naini, Shervin.;

  • 作者单位

    Clemson University.;

  • 授予单位 Clemson University.;
  • 学科 Mechanical engineering.
  • 学位 M.Engr.
  • 年度 2015
  • 页码 105 p.
  • 总页数 105
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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