Cooling Ability
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2021 ◽  
pp. 073490412110301
Author(s):  
Yawei Wang ◽  
Gaowan Zou ◽  
Conglin Liu ◽  
Y Gao

The Halon 1301 fixed gas fire extinguishing system used in ship engine rooms has been banned from production all over the world, because halon destroys the ozone layer. Therefore, it is necessary to find an environmentally friendly, compatible and efficient alternative firefighting system. In this study, we performed fire extinguishing tests in an ISO9705 standard room for four alternative fire extinguishing agents, as well as Halon 1301. The fire extinguishing efficiency of each agent was determined based on its cooling effect, dilution effect of oxygen concentration, the extinguishing time of the oil pool fire and the re-ignition probability of the wood stack. The test results provide data support for the selection of alternatives of Halon 1301 from the aspect of fire extinguishing efficiency. Among these results, Novec 1230 had the best ability to put out the oil pool fire, and HFC-227ea suppressed the wood stack fire the best. The difference between the cooling ability of each fire extinguishing agent was small, and the inert gas (IG-541) displayed the best ability to dilute oxygen. Hot aerosol required the longest time to extinguish fire. Consequently, under the existing design standards, HFC-227ea had the better firefighting efficiency, more suitable to replace Halon 1301.


Science ◽  
2021 ◽  
pp. eabi5484
Author(s):  
Shaoning Zeng ◽  
Sijie Pian ◽  
Minyu Su ◽  
Zhuning Wang ◽  
Maoqi Wu ◽  
...  

Incorporating passive radiative cooling structures into personal thermal management technologies could effectively defend human against the intensifying global climate change. We show that large scale woven metafabrics can provide high emissivity (94.5%) in the atmospheric window and reflectivity (92.4%) in the solar spectrum because the hierarchical-morphology design of the randomly dispersed scatterers throughout the metafabric. Through scalable industrial textile manufacturing routes, our metafabrics exhibit excellent mechanical strength, waterproofness, and breathability for commercial clothing while maintaining efficient radiative cooling ability. Practical application tests demonstrated the human body covered by our metafabric could be cooled down ~4.8°C lower than that covered by commercial cotton fabric. The cost-effectiveness and high-performance of our metafabrics present great advantages for intelligent garments, smart textiles, and passive radiative cooling applications.


Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2986
Author(s):  
Ling Lin ◽  
Haiyan Mao ◽  
Ziyin Li ◽  
Wenyao Li ◽  
Chaoxia Wang

Optically active polymers are promising multifunctional materials with great application potentials. Herein, environmentally friendly optically active polyurethanes (OPUs) were obtained by introducing rotatory binaphthol monomer to polyurethane. The influence of binaphthol monomer content on the structure, mechanical properties, infrared emissivity, and thermal insulation of OPUs was studied intensively. Structure characterization indicated that the optically active polyurethanes have been successfully synthesized. The OPU synthesized with BIMOL and BDO at the mole ratio of 1:1 presented better thermal resistance. In addition, OPUs showed enhanced tensile strength and stretchability with the increase of BINOL content to a certain extent due to its rigid structural features and high molecular weight. The optically active polyurethanes showed lower infrared emissivity values (8–14 μm) than waterborne polyurethane (WPU), and the infrared emissivity decreased from 0.850 to 0.572 as the content of the BINOL monomer increased. Moreover, OPU4 exhibited the best heat insulation and cooling ability with about a 7 °C temperature difference. The thus-synthesized optically active polyurethanes provide an effective solution for developing highly effective thermal insulation materials.


Author(s):  
Nidal H. Abu-Hamdeh ◽  
Ammar A. Melaibari ◽  
Thamer S. Alquthami ◽  
Ahmed Khoshaim ◽  
Hakan F. Oztop ◽  
...  

Urban Climate ◽  
2021 ◽  
Vol 35 ◽  
pp. 100743
Author(s):  
Mahyar Masoudi ◽  
Puay Yok Tan ◽  
Marjan Fadaei

2021 ◽  
pp. 197-197
Author(s):  
Manish Deshmukh ◽  
Jitendra Satpute ◽  
Nikhil Purwant ◽  
Dheeraj Deshmukh ◽  
Sandip Chavhan

The current work investigates experimental characteristics of the Photovoltaic Thermal system integrated with CuO-Water spiral flow heat exchanger and compared with non-cooled PV module. The work describes detailed procedure of Nanoparticles (NPs) preparation, SEM characterizations and heat extraction characteristics of Nanofluid (NFs) in PVT application. The heat exchanger was pasted at the back of polycrystalline PV module to form PVT system to examine cooling ability, power generation, thermal-electrical yield and overall efficiency at a different volume concentration of CuO NPs at steady mass flow rate of 0.08 kg/sec. From the experiments, it was concluded that the CuO-Water NFs assisted to lessen surface temperature of PV module by extracting heat that enhanced electrical efficiency by an average of 3.53%. It was also seen that electrical and thermal performance was improved at higher volume concentration and overall efficiency of 30.77% and 36.59 % were obtained at 0.01% and 0.03% of volume concentration.


2020 ◽  
Vol 220 ◽  
pp. 106390
Author(s):  
Lorenzo Segabinazzi ◽  
Igor Canisso ◽  
Marcio Teoro do Carmo ◽  
Sidnei Oliveira ◽  
Camila Freitas Dell’Aqua ◽  
...  

Nano Letters ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 6974-6980
Author(s):  
Rongkang Zhu ◽  
Dawei Hu ◽  
Zhi Chen ◽  
Xiaobao Xu ◽  
Yousheng Zou ◽  
...  

2020 ◽  
Vol 10 (10) ◽  
pp. 3603
Author(s):  
Matija Hribersek ◽  
Lucijano Berus ◽  
Franci Pusavec ◽  
Simon Klancnik

This paper explains liquefied nitrogen’s cooling ability on a nickel super alloy called Inconel 718. A set of experiments was performed where the Inconel 718 plate was cooled by a moving liquefied nitrogen nozzle with changing the input parameters. Based on the experimental data, the empirical model was designed by an adaptive neuro-fuzzy inference system (ANFIS) and optimized with the particle swarm optimization algorithm (PSO), with the aim to predict the cooling rate (temperature) of the used media. The research has shown that the velocity of the nozzle has a significant impact on its cooling ability, among other factors such as depth and distance. Conducted experimental results were used as a learning set for the ANFIS model’s construction and validated via k-fold cross-validation. Optimization of the ANFIS’s external input parameters was also performed with the particle swarm optimization algorithm. The best results achieved by the optimized ANFIS structure had test root mean squared error ( t e s t   R M S E ) = 0.2620 , and t e s t   R 2 = 0.8585 , proving the high modeling ability of the proposed method. The completed research contributes to knowledge of the field of defining liquefied nitrogen’s cooling ability, which has an impact on the surface characteristics of the machined parts.


2020 ◽  
Vol 494 (2) ◽  
pp. 2851-2860 ◽  
Author(s):  
Sunmyon Chon ◽  
Kazuyuki Omukai

ABSTRACT Direct collapse black hole (DCBH) formation with mass ≳105 M⊙ is a promising scenario for the origin of high-redshift supermassive black holes. It has usually been supposed that the DCBH can only form in the primordial gas since the metal enrichment enhances the cooling ability and causes the fragmentation into smaller pieces. What actually happens in such an environment, however, has not been explored in detail. Here, we study the impact of the metal enrichment on the clouds, conducting hydrodynamical simulations to follow the cloud evolution in cases with different degree of the metal enrichment Z/Z⊙ = 10−6 to 10−3. Below Z/Z⊙ = 10−6, metallicity has no effect and supermassive stars form along with a small number of low-mass stars. With more metallicity $Z/\mathrm{ Z}_{\odot } \gtrsim5 \times 10^{-6}$, although the dust cooling indeed promotes fragmentation of the cloud core and produces about a few thousand low-mass stars, the accreting flow preferentially feeds the gas to the central massive stars, which grows supermassive as in the primordial case. We term this formation mode as the super competitive accretion, where only the central few stars grow supermassive while a large number of other stars are competing for the gas reservoir. Once the metallicity exceeds 10−3 Z⊙ and metal-line cooling becomes operative, the central star cannot grow supermassive due to lowered accretion rate. Supermassive star formation by the super competitive accretion opens up a new window for seed BHs, which relaxes the condition on metallicity and enhances the seed BH abundance.


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