SYNTHETIC EVALUATION OF THERMAL ENVIRONMENT BY HEAT EXCHANGE BETWEEN SIMPLE GEOMETRIC SHAPE BODY AND EVIRONMENT : 1. COOLING POWER BETWEEN AMBIENT ENVIRONMENT AND BLACK SPHERES IN TEMPERATURE DROP COURSE

1981 ◽  
Vol 299 (0) ◽  
pp. 83-93
Author(s):  
Jang Yeul Sohn ◽  
Norio Isoda ◽  
Masayuki Matsui ◽  
Yotaro Kobayashi
Keyword(s):  
Heat Exchange ◽  
Thermal Environment ◽  
Temperature Drop ◽  
Geometric Shape ◽  
Cooling Power ◽  
Ambient Environment ◽  
Simple Geometric Shape ◽  
Synthetic Evaluation

Newgrange — Science or Symbolizm

1994 ◽  
Vol 60 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Andrew B. Powell
Keyword(s):  
Scientific Discourse ◽  
Geometric Shape ◽  
Mortuary Practices ◽  
Political Control ◽  
Spatial Relationships ◽  
Left And Right ◽  
Unit Of Length ◽  
Simple Geometric Shape

The Newgrange passage tomb is examined for evidence of ‘Neolithic science’. Claims that it incorporated an astronomical alignment, and was constructed using Pythagorean geometry and the megalithic yard are reviewed as are scientific interpretations of its art. A new analysis of the tomb's structure reveals that it was based on a simple geometric shape measurable by a 13.1 m unit of length. The locations of particular motifs and decorated surfaces are shown to conform to the spatial relationships evident in the tomb's form. These are defined in terms of oppositions between left and right, front and back, inside and outside, visible and hidden, as well as making reference to symbols found in the art of the neighbouring passage tomb at Knowth.These features are interpreted, not as evidence of a specificically scientific discourse in the Irish Neolithic, but as the elaboration of elements common to the passage tomb ritual discourse. Competition for political control, in the context of mortuary practices, resulted in the increasing formalization and rigid interpretation of passage tomb symbolizm, and the ritualization of new areas of knowledge.

A study on the thermal environment of historical villages with ‘comb-like’ layout in southern China

2016 ◽  
Vol 27 (5) ◽  
pp. 658-664
Author(s):  
Li Tang ◽  
Nan Zhang
Keyword(s):  
Thermal Environment ◽  
Sustainable Design ◽  
Southern China ◽  
Landscape Design ◽  
Practical Significance ◽  
Local Climate ◽  
Ambient Environment ◽  
Design Concepts ◽  
Geographical Environment

Historic settlements adapting to local climate and geographical environment contain rich and precious scientific design concepts, which should be investigated extensively. This paper is a study on the sustainable design and planning experiences of Chinese historic settlements. In this study, the thermal environment of Jin-Jiang-Li village with ‘comb-like’ layout in the southern China was simulated to evaluate the interactions between layout, landscape design, and ambient environment. The study has illustrated that the layout as well as the presence of water and vegetation would have an obvious-reducing effect and could play a very important role in improving the microclimate of historic settlements. The findings of our study have an essential practical significance for creating modern sustainable human environments and adapting to the changing modern climate.

Theoretical Study of a Flexible Wiretype Joule Thomson Micro-Refrigerator for Use in Cryosurgery

2010 ◽  
Author(s):  
Adhika Widyaparaga ◽  
Masashi Kuwamoto ◽  
Naoya Sakoda ◽  
Masamichi Kohno ◽  
Yasuyuki Takata
Keyword(s):  
Heat Transfer ◽  
Temperature Drop ◽  
Cooling Power ◽  
Evaporator Temperature ◽  
Flow And Heat Transfer ◽  
Microscale Flow ◽  
Poly Ether Ether Ketone ◽  
Input Variables ◽  
Experimental Trials ◽  
Gas Properties

We have developed a model capable of predicting the performance characteristics of a wiretype Joule-Thomson microcooler intended for use within a cryosurgical probe. Our objective was to be able to predict evaporator temperature, temperature distribution and cooling power using only inlet gas properties as input variables. To achieve this, the model incorporated changing gas properties due to heat transfer within the heat exchanger and isenthalpic expansion within the capillary. In consideration of inefficiencies, heat in-leak from free convection and radiation was also considered and the use of a 2D axisymmetric finite difference code allowed simulation of axial conduction. Two types of microcoolers differing in inner tube material, poly-ether-ether-ketone (PEEK) and stainless steel, were tested and simulated. CO2 was used as the coolant gas in the calculations and experimental trials for inlet pressures from 0.5 MPa to 2.0 MPa. Heat load trials of up to 550 mW along with unloaded trials were conducted. Comparisons to experiments show that the model was successfully able to obtain a good degree of accuracy. For the all PEEK microcooler in a vacuum using 2.0 MPa inlet pressure, the calculations predicted a temperature drop of 57 K and mass flow rate of 19.5 mg/s compared to measured values of 63 K and 19.4 mg/s therefore showing that conventional macroscale correlations can hold well for turbulent microscale flow and heat transfer as long as the validity of the assumptions is verified.

Near-Field Radiative Heat Exchange Analysis of a Spacecraft Waste Heat Converter Design

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Laurie Y. Carrillo ◽  
Yildiz Bayazitoglu
Keyword(s):  
Heat Exchange ◽  
Radiative Heat ◽  
Waste Heat ◽  
Thermal Environment ◽  
Near Field ◽  
Electrical Energy ◽  
Radiative Heat Exchange ◽  
Carnot Cycle ◽  
Field Plane ◽  
Cycle Efficiency

This paper presents a new design to convert spacecraft waste heat to electrical energy. The proposed device utilizes near-field radiative heat transfer incorporated with pyroelectric materials. To generate electricity, the pyroelectric materials are cyclically heated using spacecraft waste heat and cooled by the thermal environment of deep space (∼2.7 K). Near-field plane-to-plane radiative heat exchange within the device is calculated using a modified sphere-to-plane asymptotic approximation. This method is superimposed on multiple spheres to approximate a plane-to-plane environment. Silica and lithium fluoride coatings are considered in this study to maximize the near-field heat exchange. The efficiency of the device is 17% and 32% when compared to the Carnot cycle efficiency and the Curzon-Ahlborn efficiency, respectively. Initial results indicate that the device is promising but requires further development before it is manufactured for operational use. Suggestions for possible future developments to enhance the design are presented.

The contribution of solar radiation to the thermal environment of man in Antarctica

1961 ◽  
Vol 155 (959) ◽  
pp. 243-265 ◽  
Keyword(s):  
Solar Radiation ◽  
Heat Loss ◽  
Thermal Environment ◽  
Ambient Air ◽  
Whole Body ◽  
Cooling Power ◽  
Effective Surface ◽  
Heat Gain ◽  
Solar Heat ◽  
Solar Heat Gain

The parameters of solar radiation affecting man in Antarctica are considered, using data from two coastal stations and from the South Pole. Observations of solar radiation and its effects on clothing and skin temperatures of men standing on snow at Scott Base are reported. From measurements of the spectral reflectance of the outer garments and the regional thermal insulation of the clothing made subsequently, the solar heat gain at the clothing surface and its effect on heat transmission through the clothing and on heat loss to the environment were calculated. The effective surface area of the clothed body surface exposed to direct and reflected solar radiation, and the effective surface areas concerned in low temperature radiation exchange and convective heat loss, are considered. An attempt was made to determine these areas by direct measurement. The results were used to calculate values for the solar heat gain by the whole body and the cooling power of the environment under Antarctic conditions, the combined effects of which are expressed in terms of a temperature increment to be added to the ambient air temperature.

scholarly journals Inter-laboratory proficiency tests in measuring thermal insulation and evaporative resistance of clothing using the Newton-type thermal manikin

2016 ◽  
Vol 88 (4) ◽  
pp. 453-466 ◽  
Author(s):  
Magdalena Młynarczyk ◽  
George Havenith ◽  
Jean Léonard ◽  
Rui Martins ◽  
Simon Hodder
Keyword(s):  
Heat Exchange ◽  
Thermal Insulation ◽  
Thermal Environment ◽  
Reference Value ◽  
Thermal Manikin ◽  
Proficiency Tests ◽  
Evaporative Resistance ◽  
Vapor Transfer ◽  
Important Barrier ◽  
Wet Heat

Clothing acts as an important barrier for heat and vapor transfer between the human body and the environment. Parameters that could describe that transfer include, inter alia, thermal insulation (the so-called dry heat exchange) and evaporative resistance (the so-called wet heat exchange). Once the above-mentioned parameters are determined, it is possible to consciously adapt clothing ensembles to the existing thermal environment in the workplace. In order to validate the mentioned method of thermal insulation and evaporative resistance measurements, proficiency tests (PTs) were organized. The main goal of the PT was to compare thermal insulation and evaporative resistance for one set of clothing using the Newton-type thermal manikin. In total, four laboratories participated in the PT study. The reference value of the thermal insulation ( It) and evaporative resistance ( Ret) were calculated as the mean of all the results. The assessment criteria included permissible errors for thermal insulation and evaporative resistance measurements, which were 4% and 10%, respectively. Calculations included, inter alia, z-scores and indicators, such as the inter-laboratory coefficient of variation or the reproducibility limit. The results contribute to the worldwide discussion on standardized studies of evaporative resistance of clothing.

Transport Through Single-Hole Baffles in Industry Hydrothermal Autoclaves With Three-Dimensional Flows

Volume 3 ◽  
2004 ◽  
Author(s):  
Hongmin Li ◽  
Minel J. Braun ◽  
Edward A. Evans ◽  
G.-X. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Molecular Diffusion ◽  
Thermal Environment ◽  
Three Dimensional ◽  
Heat Transfer Analysis ◽  
Heat Flow Rate ◽  
Flow Strength ◽  
Fluid Exchange ◽  
Single Hole

Hydrothermal growth is the industrial preference to obtain high quality piezoelectric crystals. The industry growth process is carried out in autoclaves, cylindrical containers filled with an aqueous solution. The solution flows in industry autoclaves during growth are usually three-dimensional. A baffle is normally used to partition an autoclave into two chambers and reduce flow strength. In this paper transport through single-hole baffles of various are a openings in the three-dimensional flow is investigated systematically. It was found that a single-hole baffle is effective in controlling the fluid exchange and heat transfer between the two chambers. A smaller baffle opening leads to a more uniform thermal environment for growth. Flow structure and heat transfer data show that there is a pair of steady flow streams between the two chambers. However the heat exchange carried by this pair of streams, as well as heat exchange through molecular diffusion, is negligibly small. Transport through baffle opening is dominated by turbulence diffusion. Heat transfer analysis shows that heat flow rate depends on both the baffle opening area and the area of the chamber walls.

Evolutionary Insights into the State-of-the-Art Passive Thermal Control Systems for Thermodynamic Stability of Smallsats

2020 ◽  
Vol 35 ◽  
pp. 29-45
Author(s):  
Pratik Walimbe ◽  
Shubham Padekar
Keyword(s):  
Phase Change ◽  
Control Systems ◽  
Phase Change Materials ◽  
Thermal Environment ◽  
Temperature Drop ◽  
Direct Consequence ◽  
Thermal Control ◽  
Excessive Heat ◽  
Trade Offs ◽  
Surface Finishes

‘Smallsats,’ originated in the 1990s and popularized again since 2005, is a newly emerging miniaturized form of conventional satellites. Characterized by low mass (usually under 500 kg) and compact dimensions, Smallsats are one of the most sought-after forms of satellites, thanks to the ease offered by the lightweight. However, this privilege brings with itself the significant impediments such as excessive heat generation arising from the compact stature during peak hours of operation, external heat load as a result of radiation. These heat loads manifest themselves as the direct solar flux, earth’s albedo, and earth’s infrared radiation. Sudden temperature drop within the eclipse region results in the permanent-equipmental damage of the electronic circuitry involved, the direct consequence of which is the out-of-tolerance performance of the satellite. Thermal Control Systems (TCS) is the most plausible solution in this regard whose chief objective in any spacecraft or a satellite is to maintain all the subsystems along with the payload components within the stipulated temperature limits for each mission phase. This paper presents the passive thermal control systems (PTCS) in cube-sats. Starting with the discussion of the thermal environment, typical concepts like albedo, earth IR are shed light on. Subsequent discussions follow the study of thermal surface finishes and multi-layer insulations (MLI). Finally, the applications of phase-change materials (PCM) in thermal control systems of cube-sats are introduced. The constant trade-offs between the optimal thermal finish and the overall performance, arising due to incurrence of contamination during synthesis, SLI-MLI thickness and cost associated with increasing thickness and the phase-change materials (PCM’s) and their compatibility, have always been at the pin-point of the research. The widespread importance of thermal control systems is attributed to its ability to ensure the meetings of the gradient requirements, a parameter playing a crucial role in spacecraft dynamics.

Sign in / Sign up

Export Citation Format

Share Document