The torso cooling of vests incorporated with phase change materials: a sweat evaporation perspective

2012 ◽  
Vol 83 (4) ◽  
pp. 418-425 ◽  
Author(s):  
Mengmeng Zhao ◽  
Chuansi Gao ◽  
Faming Wang ◽  
Kalev Kuklane ◽  
Ingvar Holmér ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Phase Change ◽  
Protective Clothing ◽  
Phase Change Materials ◽  
Thermal Manikin ◽  
Evaporative Resistance ◽  
Melting Temperatures ◽  
Sweat Production ◽  
Hot Environments ◽  
Sweat Evaporation

Cooling vests incorporated with phase change materials (PCMs) add extra insulation and restrict sweat evaporation. It is still unclear how much cooling benefit they can provide. The aim of this study was to investigate the torso cooling of the PCM vests in two hot environments: hot humid (HH, 34°C, 75% relative humidity (RH)) and hot dry (HD, 34°C, 37% RH). A pre-wetted torso fabric skin was used to simulate torso sweating on a thermal manikin. Three cooling vests incorporated with three melting temperatures ( Tm) of PCMs were tested ( Tm = 21°C, Tm = 24°C and Tm = 28°C). They were worn under a military ensemble (total thermal insulation 1.60 clo; evaporative resistance 0.0516 kPaċm2/W), respectively. In a HH environment all the three cooling vests provided effective torso cooling; in a HD environment the cooling benefit was negative. In both environmental conditions, the evaporative cooling was greatly restricted by the cooling vests. The study indicated that when wearing the protective clothing with the relatively low evaporative resistance and when sweat production was high, the cooling vests were effective in a HH environment, but not in a HD environment.

scholarly journals Characteristics of Specialised Firefighter Clothing Used in Poland – the Thermal Parameters

2020 ◽  
Vol 28 (1(139)) ◽  
pp. 65-70
Author(s):  
Magdalena Młynarczyk
Keyword(s):  
Thermal Insulation ◽  
Protective Clothing ◽  
Thermal Parameters ◽  
Thermal Manikin ◽  
Test Results ◽  
Evaporative Resistance ◽  
Different Types ◽  
Local Thermal Insulation ◽  
Materials Used ◽  
The Impact

This paper describes the characteristic thermal parameters of firefighters’ personal protective clothing (FFPPC) used in Poland. The total thermal insulation and evaporative resistance of three different types of FFPPC were measured and used on a thermal manikin. Next, the results were compared. Based on the analyses and calculations of the test results, it was shown that FFPPC provides a barrier to the heat exchange between the user and the surrounding environment. Differences in the local thermal insulation can be triggered not only by the material used but they can also be attributable to clothes fitted on the manikin. The biggest differences can be noted on the segments forming part of the manikin’s trunk. No difference was found in the evaporative resistance between the clothes tested. In order to examine further the impact of the materials used on thermal parameters of protective clothing, it is necessary to carry out an analysis of the impact of individual layers.

Suitability Assessment and Experimental Characterization of Phase Change Materials for Energy Conservation in Indian Buildings

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Rajat Saxena ◽  
Naman Agarwal ◽  
Dibakar Rakshit ◽  
S. C. Kaushik
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Thermal Capacity ◽  
Climatic Conditions ◽  
Melting Temperatures ◽  
Suitability Assessment ◽  
Efficiency Measures ◽  
Prime Concern ◽  
Change Temperature ◽  
And Performance

Abstract With increasing energy consumption in buildings, energy efficiency measures are matter of prime concern. A huge portion of energy consumed in buildings is used for regulating the thermal comfort. A solution to this is to incorporate phase change material (PCM) within the building elements which increases their overall thermal capacity. In the present study, the temperature of inner room surface, with and without PCM incorporation, is calculated for composite climate of Delhi. The analysis of PCM sandwiched walls has been performed. The performance analysis of five PCMs, having different melting temperatures, is carried out with nodal temperatures as the output. The results show that a phase change temperature range of 34–38 °C is suitable for peak summer conditions of Delhi. It is also observed that due to the low thermal conductivity of PCMs, they act as both storage medium and insulation, thus reducing temperature fluctuation during summer/winter. Based on the simulation, three PCMs were found suitable and hence were experimentally tested for their characteristic charging and discharging properties and performance, using differential scanning calorimeter (DSC). Based on the characterization results, it is concluded that two commercially available PCMs (Eicosane and OM35) are suitable for Delhi. All the other PCMs have also been simulated for different climatic conditions in India and their impact on heat gain has been assessed.

scholarly journals Multiscale Modelling Approach Targeting Optimisation of PCM into Constructive Solutions for Overheating Mitigation in Buildings

2020 ◽  
Vol 10 (22) ◽  
pp. 8009
Author(s):  
António Figueiredo ◽  
Romeu Vicente ◽  
Rui Oliveira ◽  
Fernanda Rodrigues ◽  
António Samagaio
Keyword(s):  
Phase Change ◽  
Energy Demand ◽  
Phase Change Materials ◽  
Supply And Demand ◽  
Energy Performance ◽  
Simulation Software ◽  
Rate Reduction ◽  
Melting Temperatures ◽  
Detached House ◽  
Global Energy Supply

Nowadays, the rising gap between the global energy supply and demand is a well-known circumstance in society. Exploring the solution to invert this tendency leads to several different scenarios of energy demand saving strategies that can be improved using phase change materials (PCM), especially in cold-formed steel-framed buildings. The present research reports the overheating (indoor air temperature above 26 °C expressed as an annualized percentage rate) reduction in south-oriented compartments and energy performance of a detached house located in the Aveiro region, in Portugal. An optimisation study was performed incorporating different phase change materials (PCMs) solutions and their position in the exterior envelope focusing overheating rate reduction and heating demand. The optimisations were managed by using a hybrid evolutionary algorithm coupled with EnergyPlus® simulation software. The overheating risk was reduced by up to 24% in the cooling season, for the case of the building compartments with south orientation. Thus, the use of construction solutions using PCMs with different melting temperatures revealed to be a good strategy to maximise PCM efficiency as a passive solution.

scholarly journals Molecular structure and melting: implications for phase change materials

2018 ◽  
Vol 96 (7) ◽  
pp. 722-729 ◽  
Author(s):  
John A. Noël ◽  
Samer Kahwaji ◽  
Mary Anne White
Keyword(s):  
Molecular Structure ◽  
Phase Change ◽  
Phase Change Materials ◽  
Alkyl Chains ◽  
Melting Temperatures ◽  
Enthalpy Changes ◽  
Melting Properties ◽  
Load Leveling ◽  
The Relationship ◽  
Selection Of

Phase change materials (PCMs) offer a promising technology for thermal energy storage, load leveling, and peak shifting applications. A desirable PCM has a melting temperature within the temperature boundaries of its application and a high change in enthalpy on melting. Knowledge of the relationships between these thermodynamic properties and molecular structure would advance informed selection of PCM candidates for a given application. In the present investigation, the relationship between structure (length of alkyl chains) and melting properties has been investigated for isomeric esters, showing that esters containing longer individual alkyl chains have higher melting temperatures and higher enthalpy changes on melting. The melting entropy changes, however, are relatively independent of the alkyl chain distribution.

Studies of Ge-Sb-Te Phase Change Materials At and Above Melting Temperatures and Set to Reset Transition of Memory Devices

2010 ◽  
Vol 1251 ◽  
Author(s):  
Semyon D Savransky ◽  
Guy Wicker
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Memory Devices ◽  
Melting Temperatures ◽  
Electrical Studies ◽  
Melting Region ◽  
Electrical Resistivities ◽  
Multi Level ◽  
Selection For ◽  
Change Memory

AbstractThe results of calorimetric and electrical studies of bulk Ge2Sb2Te5 and GeSb2Te4 alloys around melting temperature Tm are presented together with characteristics of phase-change memory devices from such alloys. The endothermic melting region is wider in Ge2Sb2Te5 than GeSb2Te4. Electrical resistivities of the alloys in this region have semiconductor characteristics. The width of the melting region correlates with breadth of set to reset transition in devices. This empirical correlation is probably important for alloy selection for multi-level memory cells.

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