A Statistical Study to Evaluate the Performance of Liquid Cooling Garments Considering Thermal Comfort

2019 ◽  
Author(s):  
Weicheng Shu ◽  
Jiawen Wang ◽  
Xinfeng Zhang ◽  
Xiaobing Luo
Keyword(s):  
Thermal Comfort ◽  
Optimization Design ◽  
Working Time ◽  
Orthogonal Experimental Design ◽  
Thermal Manikin ◽  
Inlet Temperature ◽  
Liquid Cooling ◽  
Time Ratio ◽  
Key Factor ◽  
Cooling Garments

Abstract Liquid cooling garments (LCGs) are considered a feasible cooling equipment to protect individuals from hyperthermia and heat-related illness when working in extremely hot and stressful environments. So far, the goals for optimization design of LCGs are mostly from the perspective of enhancing its efficiency and duration working time. However, thermal comfort is the key factor which is often not considered. In fact, there are many situations that may cause discomfort. For example, as the ice melts, the inlet temperature of the liquid cooling vest changes constantly resulting in the change of thermal states of the human body, which lead to discomfort of human. So, it is very significative to develop a method to evaluate the performance of LCGs considering thermal comfort. In this paper, an uncomfortable time ratio was proposed to evaluate the performance of LCGs considering thermal comfort. It defined the proportion of uncomfortable time including overcooling and overheating in the entire working time. Series of tests were conducted by a modified thermal manikin method to evaluate the thermal properties. According to the analyses, the duration working time was 82.77 min, while the uncomfortable time ratio was too large, up to 57.6 %. It showed that the requirement of comfort should be considered when optimizing the performance of LCGs. The influences of different parameters such as the volume of ice, flowrate, inlet temperature on the performance of LCGs were investigated through orthogonal experimental design. The statistical analysis illustrated that the influence of the volume of ice on the uncomfortable time ratio is greater than that of flowrate and ambient temperature. It is concluded that this method is useful for the control and design of LCGs considering thermal comfort.

A Statistical Study to Evaluate the Performance of Liquid Cooling Garments Considering Thermal Comfort

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Weicheng Shu ◽  
Jiawen Wang ◽  
Xinfeng Zhang ◽  
Xiaobing Luo
Keyword(s):  
Thermal Comfort ◽  
Optimization Design ◽  
Working Time ◽  
Orthogonal Experimental Design ◽  
Thermal Manikin ◽  
Inlet Temperature ◽  
Liquid Cooling ◽  
Time Ratio ◽  
Key Factor ◽  
Cooling Garments

Abstract Liquid cooling garments (LCGs) are considered feasible cooling equipment to protect individuals from hyperthermia and heat-related illness when working in extremely hot and stressful environments. So far, the goals for the optimization design of LCGs are mostly from the perspective of enhancing its efficiency and working time. However, thermal comfort is the key factor that is often not considered. In fact, many situations may cause discomfort. For example, the inlet temperature of the liquid-cooling vest changes constantly resulting in the change of thermal states of the human body. So, it is very significative to develop a method to evaluate the performance of LCGs considering thermal comfort. In this paper, an uncomfortable time ratio was proposed to evaluate the performance of LCGs considering thermal comfort. A series of tests were conducted by a modified thermal manikin method to evaluate the thermal properties. According to the analyses, the duration working time was 82.77 min, while the uncomfortable time ratio was too large, up to 57.6%. It showed that the thermal comfort should be considered when optimizing the performance of LCGs. The influences of different parameters such as volume of ice, flowrate, inlet temperature on the performance of LCGs were investigated through orthogonal experimental design. The statistical analysis illustrated that the influence of the volume of ice on the uncomfortable time ratio is greater than that of flowrate and ambient temperature. It is concluded that this method is useful for the control and design of LCGs considering thermal comfort.

A Smart Temperature-Regulating Garment for Portable, High-Efficiency and Comfortable Cooling

2021 ◽  
Author(s):  
Weicheng Shu ◽  
Xinfeng Zhang ◽  
Xuan Yang ◽  
Xiaobing Luo
Keyword(s):  
Thermal Comfort ◽  
High Efficiency ◽  
Working Time ◽  
Regulation System ◽  
Thermal Manikin ◽  
Inlet Temperature ◽  
Liquid Cooling ◽  
Work Duration ◽  
Smart Control ◽  
Cooling Garment

Abstract In a conventional liquid cooling garment (LCG), overcooling of the water inlet temperature shortens the working time and worsens thermal comfort. Such problems have not been well solved so far. In this study, we propose a smart cooling garment with a developed temperature regulation system, effectively reducing unnecessary loss of power consumption and hence extending the work duration. Testing on a thermal manikin was conducted to evaluate the performance of temperature-regulating LCG. The results showed that, compared to the conventional LCG, the proposed system achieved the rapid and accurate adjustment of water temperature, improved the working time by more than 37% with the total weight barely increased, and ensured the thermal comfort of the wearers. The developed LCG opens the possibility for the smart control of the temperature, fitting for the user's preferences regarding the working time and thermal comfort sensations.

173. Comparing Thermal Manikin and Physiological Testing Results to Assess the Performance of Liquid Cooling Garments

2004 ◽  
Author(s):  
K. Semeniuk ◽  
J. Dionne ◽  
A. Makris ◽  
T. Bernard ◽  
C. Ashley ◽  
...  
Keyword(s):  
Thermal Manikin ◽  
Liquid Cooling ◽  
Cooling Garments

Simulation of Efficiency of Liquid Cooling Garments

2011 ◽  
Vol 331 ◽  
pp. 636-639
Author(s):  
Ming Wei Tian ◽  
Su Kang Zhu ◽  
Ning Pan
Keyword(s):  
Dynamic Equilibrium ◽  
Three Dimensional ◽  
Characteristic Parameter ◽  
Thermal Manikin ◽  
Liquid Cooling ◽  
Effective Form ◽  
Equilibrium Level ◽  
Cooling Effects ◽  
Cooling Garment ◽  
Cooling Garments

Liquid cooling garment (LCG) is treated as one kind of effective form-fitting garment applied to remove and release extra heat efficiently from human body whose internal temperature can be easily maintained at a safe dynamic equilibrium level under the severe boundary conditions. In this paper, firstly, two specialized types of liquid cooling garments, wrapped around thermal manikin, are designed as the three-dimensional heat-flux coupling models that are solved numerically using a finite element method, and then the effective cooling temperatures of the thermal manikin skin are proposed as the characteristic parameter to evaluate the cooling effects of these garments. Finally, A comparison of thus effective cooling temperature with the experiment data from the existing reference are shown that this simulation model develops very reliable results for the heat transfer between liquid cooling garments and thermal manikin.

Investigation on thermal comfort of the uniform for workers in tropical monsoon climates

2020 ◽  
Vol 32 (6) ◽  
pp. 849-868
Author(s):  
Jingxian Xu ◽  
Huijuan Liu ◽  
Yunyi Wang ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Thermal Comfort ◽  
Dynamic Condition ◽  
Thermal Manikin ◽  
Content Type ◽  
Wind Speeds ◽  
Subjective Perceptions ◽  
Tropical Monsoon ◽  
Four Levels ◽  
Thermal Insulations

PurposeThis study aims to investigate the heat transfer mechanism of the uniforms used by people working in hot, humid and windy environments. Furthermore, the effectiveness of an opening structure added to the armpit of the uniforms in improving thermal comfort was comparatively examined.Design/methodology/approachA set of uniforms was tested with the opening at the armpit alternatively zipped or unzipped. Thermal manikin and human tests were performed in a climatic chamber simulating the specific environmental conditions, including wind speeds at four levels (0.15, 0.5, 2, 4 m/s) and relative humidities at two levels (50 and 85%). Static and dynamic thermal insulations of clothing (IT) were examined by the thermal manikin tests. The human bodies' thermal responses, including heart rates (HR), eardrum temperatures (Te), skin temperatures (Tsk) and subjective perceptions, were given by the human tests.FindingsSpecial mechanisms of heat transfer in the specific uniforms used in tropical monsoon climates were revealed. Reductions on IT were caused by the movement of the human body and the environmental wind, and the empirical equations would underestimate this reduction. The opening at the armpit was able to prompt more heat transfer under dynamic condition, with reducing the IT by 11.8%, lowering the mean Tsk by 0.92°C, and significantly improving the subjective perceptions (p < 0.05). The heat exhaustion was alleviated with lowering the Te by 0.32°C.Originality/valueThis study managed to improve the thermal performance of uniforms for workers under unforgiving conditions. The evaluation and design methods introduced by this study provided practical guidance for similar products with strict dress codes and cost control requirements based on the findings from thorough product tests and analysis.

scholarly journals Influence of Masks Protecting against SARS-CoV-2 on Thermal Comfort

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3315
Author(s):  
Ewa Zender-Świercz ◽  
Marek Telejko ◽  
Beata Galiszewska
Keyword(s):  
Thermal Comfort ◽  
Public Spaces ◽  
Point Of View ◽  
The Other ◽  
Health Policies ◽  
Thermal Manikin ◽  
Public Health Policies ◽  
Protective Shield ◽  
Full Face ◽  
The Impact

Due to the spread of the SARS-CoV-2 virus, most countries have tightened their public health policies. One way to limit the spread of the virus is to make mouth and nose cover compulsory in public spaces. The article presents the impact of wearing masks on the perception of thermal comfort. The following masks were analysed: FFP2, cotton, medical, PM2.5, half-face protective shield plastic and full-face protective shield plastic. The research was carried out for two scenarios of an ambient temperature: −20 and 30 °C. A thermal manikin was used for the tests. In the case of when a temperature equals 20 °C, the dry masks increase comfort, both general and local, while wet masks reduce comfort. On the other hand, at 30 °C, only wet masks do not increase discomfort. In addition, moist masks require less heat flux to achieve a certain skin temperature. However, it should be remembered that it is not advisable to wet the masks from the health point of view.

Characterization of an Isolated Hybrid Cooled Server With Failure Scenarios Using Warm Water Cooling

2017 ◽  
Author(s):  
Uschas Chowdhury ◽  
Manasa Sahini ◽  
Ashwin Siddarth ◽  
Dereje Agonafer ◽  
Steve Branton
Keyword(s):  
Energy Consumption ◽  
Data Centers ◽  
Cooling System ◽  
Warm Water ◽  
Alternative Methods ◽  
Inlet Temperature ◽  
Cooling Efficiency ◽  
Water Cooling ◽  
Liquid Cooling ◽  
Total Energy Consumption

Modern day data centers are operated at high power for increased power density, maintenance, and cooling which covers almost 2 percent (70 billion kilowatt-hours) of the total energy consumption in the US. IT components and cooling system occupy the major portion of this energy consumption. Although data centers are designed to perform efficiently, cooling the high-density components is still a challenge. So, alternative methods to improve the cooling efficiency has become the drive to reduce the cooling cost. As liquid cooling is more efficient for high specific heat capacity, density, and thermal conductivity, hybrid cooling can offer the advantage of liquid cooling of high heat generating components in the traditional air-cooled servers. In this experiment, a 1U server is equipped with cold plate to cool the CPUs while the rest of the components are cooled by fans. In this study, predictive fan and pump failure analysis are performed which also helps to explore the options for redundancy and to reduce the cooling cost by improving cooling efficiency. Redundancy requires the knowledge of planned and unplanned system failures. As the main heat generating components are cooled by liquid, warm water cooling can be employed to observe the effects of raised inlet conditions in a hybrid cooled server with failure scenarios. The ASHRAE guidance class W4 for liquid cooling is chosen for our experiment to operate in a range from 25°C – 45°C. The experiments are conducted separately for the pump and fan failure scenarios. Computational load of idle, 10%, 30%, 50%, 70% and 98% are applied while powering only one pump and the miniature dry cooler fans are controlled externally to maintain constant inlet temperature of the coolant. As the rest of components such as DIMMs & PCH are cooled by air, maximum utilization for memory is applied while reducing the number fans in each case for fan failure scenario. The components temperatures and power consumption are recorded in each case for performance analysis.

A Novel Elastomer Simulated Skin Applied in Measurement of Extravehicular Liquid Cooling Garment

2011 ◽  
Vol 239-242 ◽  
pp. 908-911
Author(s):  
Kai Yang ◽  
Ming Li Jiao
Keyword(s):  
Natural Rubber Latex ◽  
Thermoplastic Elastomer ◽  
Ethylene Vinyl Acetate ◽  
Fuzzy Decision Making ◽  
Thermal Manikin ◽  
Liquid Cooling ◽  
Series Of Experiments ◽  
Cooling Garment ◽  
Heat Property ◽  
Fuzzy Mathematic

A novel thermoplastic elastomer was applied in the measurement of extravehicular liquid cooling garment and the satisfying result in improving the heat dissipating capacity of liquid cooling garment was achieved. Firstly, five kinds of elastomer were selected, which were ethylene-vinyl acetate copolymer (EVA), high temperature vulcanized silicone rubber (HTV), medical used silicon rubber (MSR), natural rubber latex (NRL) and thermoplastic SBS complex (TPR). To evaluate the synthetic performance of these materials, a series of experiments characterizing material’s mechanical and thermodynamic properties was performed, including tensile and compression test, heat property test and so on. Meanwhile, fuzzy mathematic method was employed to get parameters’ weight distribution, and then fuzzy decision-making method was adopted to perform synthetic evaluation, which showed that TPR had satisfying optimization performance and can be used as simulated skin in thermal manikin. Finally, to verify the function of TPR simulated skin, comparative experiments were performed in climate chamber when thermal manikin covered with TPR simulated skin and did not cover with TPR simulated skin. Results show that TPR simulated skin can effectively improve the heat dissipating capacity of liquid cooling garment.

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