scholarly journals The influence of an active microclimate liquid-cooled vest on heat strain alleviation

2020 ◽  
pp. 331-331
Author(s):  
Sveta Cvetanovic ◽  
Srdjan Rutic ◽  
Dejan Krstic ◽  
Stanislav Florus ◽  
Pavel Otrisal
Keyword(s):  
Cooling System ◽  
Sweat Rate ◽  
Heat Exposure ◽  
Thermal Strain ◽  
Experimental Results ◽  
Tympanic Temperature ◽  
Body Core Temperature ◽  
Liquid Cooling ◽  
Strain Testing ◽  
Body Cooling

This research was performed to test the effectiveness of the microclimate body cooling system which belongs to the group of active systems with liquid-cooled technology. The liquid cooling vest efficiency was observed concerning the physiological fitness of the standard protective set used in specific environmental conditions which imply increased thermal strain of the test subjects. Experimental results from the research are based on the examinations carried out in a thermo-physiological laboratory. Ten healthy male volunteers - test subjects aged (23.4 ? 2.4 years, weight 74 ? 7 kg, and height 184 ? 9 cm) were exposed to thermal strain testing (40 ?C temperature, 40?3% relative humidity, without wind) and simultaneously to physical effort caused by walking on the treadmill at a speed of 5 km/h, during 45 minutes. Tests were performed in two variants - without any cooling system (NC) and with the KewlFlow Circulatory Cooling Vest with Cooler Kit (LC). Throughout heat exposure, the subject's body core temperature (tympanic temperature - Tty), mean skin temperature (Tsk) and heart rate (HR) were measured. Furthermore, sweat rate (SwR) was calculated in order to determine all changes in the water and electrolyte status. Experimental results confirm that the results of this study have recognized the benefits of a liquid-cooled vest in lowering the thermal strain.

scholarly journals The influence of the passive evaporative cooling vest on a chemical industry workers and physiological strain level in hot conditions

2015 ◽  
Vol 69 (6) ◽  
pp. 587-594 ◽  
Author(s):  
Radovan Karkalic ◽  
Dalibor Jovanovic ◽  
Sonja Radakovic ◽  
Dusan Rajic ◽  
Biljana Petrovic ◽  
...  
Keyword(s):  
Heat Stress ◽  
Cooling System ◽  
Sweat Rate ◽  
Stress Test ◽  
Tympanic Temperature ◽  
Physiological Strain ◽  
Military Medical Academy ◽  
Hot Environment ◽  
Body Cooling ◽  
Exertional Heat Stress

The present study was conducted in order to evaluate efficiency of a personal body cooling system based on passive evaporative technologies and its effects on test subjects psycho-physiological suitability during exertional heat stress in hot environment. Performed results are based on conducted tests in climatic chamber in the Military Medical Academy Institute of Hygiene in Belgrade. Ten male test subjects were subjected to exertional heat stress test consisted of walking on motorized treadmill at a speed of 5 km/h in hot environment. Tests were performed with and without cooling system. As a physiological strain indicator the following parameters have been determined: mean skin temperature, tympanic temperature, heart rate and sweat rate. Results confirmed that cooling vest worn over the clothes was able to attenuate the physiological strain levels during exercise, when compared to identical exposure without the cooling system.

Responses of Motor-Sport Athletes to V8 Supercar Racing in Hot Conditions

2007 ◽  
Vol 2 (2) ◽  
pp. 182-191 ◽  
Author(s):  
Matt B. Brearley ◽  
James P. Finn
Keyword(s):  
Perceived Exertion ◽  
Thermal Sensation ◽  
Sweat Rate ◽  
Thermal Strain ◽  
Body Core Temperature ◽  
Hydration Status ◽  
Borg Scale ◽  
Thermal Discomfort ◽  
Body Core ◽  
Cardiovascular Strain

Background:Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.Purpose:To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.Methods:Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.Results:Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.Conclusions:Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.

scholarly journals Physiological tolerance to uncompensated heat stress in soldiers: Effects of various types of body cooling systems

2014 ◽  
Vol 71 (3) ◽  
pp. 259-264 ◽  
Author(s):  
Dalibor Jovanovic ◽  
Radovan Karkalic ◽  
Snjezana Zeba ◽  
Miroslav Pavlovic ◽  
Sonja Radakovic
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Cooling System ◽  
Tympanic Temperature ◽  
Hydration Status ◽  
Physiological Strain ◽  
Cooling Systems ◽  
Physiological Tolerance ◽  
Body Cooling ◽  
Exertional Heat Stress

Background/Aim. In military services, emergency situations when soldiers are exposed to a combination of nuclear, biological and chemical (NBC) contamination combined with heat stress, are frequent and complex. In these specific conditions, usage of personal body cooling systems may be effective in reducing heat stress. The present study was conducted in order to evaluate the efficiency of four various types of contemporary personal body cooling systems based on the ?Phase Change Material? (PCM), and its effects on soldiers? subjective comfort and physiological performance during exertional heat stress in hot environments. Methods. Ten male soldiers were voluntarily subjected to exertional heat stress tests (EHSTs) consisted of walking on a treadmill (5.5 km/h) in hot conditions (40?C) in climatic chamber, wearing NBC isolating impermeable protective suits. One of the tests was performed without any additional cooling solution (NOCOOL), and four tests were performed while using different types of cooling systems: three in a form of vests and one as underwear. Physiological strain was determined by the mean skin temperature (Tsk), tympanic temperature (Tty), and heart rate values (HR), while sweat rates (SwR) indicated changes in hydration status. Results. In all the cases EHST induced physiological response manifested through increasing Tty, HR and SwR. Compared to NOCOOL tests, when using cooling vests, Tty and Tsk were significantly lower (on 35th min, for 0.44 ? 0.03 and 0.49 ? 0.05?C, respectively; p < 0.05), as well as the average SwR (0.17 ? 0.03 L/m2/h). When using underwear, the values of given parameters were not significantly different compared to NOCOOL tests. Conclusions. Using a body cooling system based on PCM in the form of vest under NBC protective clothes during physical activity in hot conditions, reduces sweating and alleviates heat stress manifested by increased core and skin temperatures and heart rate values. These effects directly improve heat tolerance, hydration state, decrease in the risk of heat illness, and extends the duration of soldiers? exposure to extreme conditions.

Multi-objective optimization of a chip-attached micro pin fin liquid cooling system

2021 ◽  
pp. 117187
Author(s):  
Vahideh Radmard ◽  
Yaser Hadad ◽  
Srikanth Rangarajan ◽  
Cong H. Hoang ◽  
Najmeh Fallahtafti ◽  
...  
Keyword(s):  
Cooling System ◽  
Multi Objective Optimization ◽  
Liquid Cooling ◽  
Multi Objective ◽  
Pin Fin ◽  
Liquid Cooling System

The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults

2017 ◽  
Vol 14 (9) ◽  
pp. 703-711 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Robert D. Meade ◽  
Andrew W. D'Souza ◽  
Andreas D. Flouris ◽  
Stephen G. Hardcastle ◽  
...  
Keyword(s):  
Core Temperature ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Limit Values ◽  
Threshold Limit Values ◽  
Working Adults ◽  
Threshold Limit ◽  
Body Core ◽  
Safe Limits

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.

Study on Copper Cold Plate Designs for Electronics Liquid Cooling System

2006 ◽  
Author(s):  
Yi. Feng ◽  
Y. Wang ◽  
C. Y. Huang
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Cooling System ◽  
Pure Copper ◽  
Cold Plate ◽  
Performance Limits ◽  
Liquid Cooling ◽  
Cold Plates ◽  
Management Approaches ◽  
Liquid Cooling System

The increasing power consumption of microelectronic systems and the dense layout of semiconductor components leave very limited design spaces with tight constraints for the thermal solution. Conventional thermal management approaches, such as extrusion, fold-fin, and heat pipe heat sinks, are somehow reaching their performance limits, due to the geometry constraints. Currently, more studies have been carried out on the liquid cooling technologies, as the flexible tubing connection of liquid cooling system makes both the accommodation in constrained design space and the simultaneous cooling of multi heating sources feasible. To significantly improve the thermal performance of a liquid cooling system, heat exchangers with more liquid-side heat transfer area with acceptable flow pressure drop are expected. This paper focuses on the performance of seven designs of source heat exchanger (cold plate). The presented cold plates are all made in pure copper material using wire cutting, soldering, brazing, or sintering process. Enhanced heat transfer surfaces such as micro channel and cooper mesh are investigated. Detailed experiments have been conducted to understand the performance of these seven cooper cold plates. The same radiators, fan, and water pump were connected with each cooper cold plate to investigate the overall thermal performance of liquid cooling system. Water temperature readings at the inlets and outlets of radiators, pump, and colder plate have been taken to interpret the thermal resistance distribution along the cooling loop.

MK801 impairs thermoregulation in the heat

2002 ◽  
Vol 80 (3) ◽  
pp. 226-232 ◽  
Author(s):  
Frédéric Canini ◽  
Nadine Simler ◽  
Lionel Bourdon
Keyword(s):  
Locomotor Activity ◽  
Nmda Receptor ◽  
Receptor Antagonist ◽  
Core Temperature ◽  
Exposure Duration ◽  
Heat Exposure ◽  
Nmda Receptor Antagonist ◽  
Dopamine Metabolism ◽  
Body Core Temperature ◽  
Body Core

The effects of MK801 (dizocilpine), a glutamate NMDA receptor antagonist, on thermoregulation in the heat were studied in awake rats exposed to 40°C ambient temperature until their body core temperature reached 43°C. Under these conditions, MK801-treated rats exhibited enhanced locomotor activity and a steady rise in body core temperature, which reduced the heat exposure duration required to reach 43°C. Since MK801-treated rats also showed increased striatal dopaminergic metabolism at thermoneutrality, the role of dopamine in the MK801-induced impairment of thermoregulation in the heat was determined using co-treatment with SCH23390, a dopamine D1 receptor antagonist. SCH23390 normalized the locomotor activity in the heat without any effect on the heat exposure duration. These results suggest that the MK801-induced impairment of thermoregulation in the heat is related to neither a dopamine metabolism alteration nor a locomotor activity enhancement.Key words: heatstroke, NMDA receptor, thermoregulation, dopamine, locomotion.

Heat strain in Royal Navy helicopter aircrew

1999 ◽  
Vol 85 (2) ◽  
pp. 84-109
Author(s):  
J R House
Keyword(s):  
Protective Clothing ◽  
Thermal Environment ◽  
Cooling System ◽  
Heat Strain ◽  
Protective Equipment ◽  
Flight Period ◽  
Royal Navy ◽  
Liquid Cooling ◽  
And Performance ◽  
Climate Cooling

AbstractA review of the literature on heat strain and aircrew and a questionnaire survey of Royal Navy aircrew have been completed. Aircrew appreciate, some 50% from first hand experience, that heat strain can reduce their operational endurance and performance. They are at greatest risk of developing it in the pre-flight period, especially when wearing Nuclear, Biological, or Chemical (NBC) protective equipment. Several techniques they use to reduce this risk are described. Some may be of particular assistance in the field should air conditioned facilities be unavailable. However, opportunities to improve the thermal environment within the aircraft on the ground and in flight are limited as the heat generated within it and high levels of solar radiation impinging on it severely challenge air conditioning units, themselves constrained by weight and size. Other demands placed on protective clothing offer little potential to increase the rate at which aircrew can lose accumulated heat. It is concluded that an appropriate micro-climate cooling system worn next to the skin may be required to achieve truly significant reductions in heat strain. Research at the Institute of Naval Medicine has identified liquid cooling techniques which may be suitable for aircrew in all but the smallest helicopters.Any views expressed are those of the author and do not necessarily represent those of the Department.

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