Yazdanirad Saeid, Dehghan Habibollah
Department of Occupational Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran.
Int J Prev Med. 2016 Mar 1;7:47. doi: 10.4103/2008-7802.177890. eCollection 2016.
The phase change materials (PCMs) have the appropriate properties for controlling heat strain. One of the well-known PCMs is paraffin. This study aimed to design the cooling vest from the cheap commercial paraffin compound and evaluation of its effectiveness under laboratory hot conditions.
the cooling vest was made of the polyester fabric and it had 17 aluminum packs. The each of aluminum packs was filled by 135 g of prepared paraffin with a proper melting point in the range of 15-35°C. an experimental study was conducted on ten male students under warm conditions (air temperature = 40°C, relative humidity = 40%) in a climatic chamber. Each participant was tested without cooling vest and with cooling in two activities rate on treadmill to include: light (2.8 km/h) and moderate (4.8 km/h). The time of this test was 30 min in each stage. During the test, the heart rate, the oral temperature, the skin temperature were measured every 4 min. Finally, data were analyzed using the Kolmogrov-Smirnov and repeated measurement ANOVA test in SPSS 16.
The latent heat of the prepared paraffin compound and the peak of the melting point were 108 kJ/kg and 30°C, respectively. The mean and standard deviation of heart rate, oral temperature, and skin temperature with cooling vest in light activity were 103.9 (12.12) beat/min, 36.77 (0.32)°C, and 31.01 (1.96)°C and in moderate activity were 109.5 (12.57) beat/min, 36.79 (0.20)°C, and 29.69 (2.23)°C, respectively. There is a significant difference between parameters with a cooling vest and without cooling (P < 0.05).
The designed cooling vest with low cost can be used to prevent thermal strain and to increase the physiological stability against the heat. However, the latent heat of this cooling vest was low.
相变材料（PCM）具有控制热应激的合适特性。一种著名的相变材料是石蜡。本研究旨在用廉价的商用石蜡化合物设计冷却背心，并评估其在实验室热条件下的有效性。
冷却背心由聚酯织物制成，有17个铝包。每个铝包填充135克熔点在15 - 35°C范围内的制备石蜡。在气候室中对10名男学生在温暖条件下（气温 = 40°C，相对湿度 = 40%）进行了一项实验研究。每个参与者在跑步机上以两种活动速率进行测试，一种是不穿冷却背心，另一种是穿冷却背心，活动速率包括：轻度（2.8 km/h）和中度（4.8 km/h）。每个阶段的测试时间为30分钟。在测试过程中，每4分钟测量一次心率、口腔温度和皮肤温度。最后，在SPSS 16中使用Kolmogrov - Smirnov和重复测量方差分析对数据进行分析。
制备的石蜡化合物的潜热和熔点峰值分别为108 kJ/kg和30°C。穿冷却背心时，轻度活动中心率、口腔温度和皮肤温度的平均值及标准差分别为103.9（12.12）次/分钟、36.77（0.32）°C和31.01（1.96）°C，中度活动中分别为109.5（12.57）次/分钟、36.79（0.20）°C和29.69（2.23）°C。穿冷却背心和不穿冷却背心时各参数之间存在显著差异（P < 0.05）。
设计的低成本冷却背心可用于预防热应激并提高对热的生理稳定性。然而，这种冷却背心的潜热较低。
