scholarly journals Development and Experiments of an Electrothermal Driven Deep-Sea Buoyancy Control Module

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1017
Author(s):  
Jiaoyi Hou ◽  
Weifeng Zou ◽  
Zihao Li ◽  
Yongjun Gong ◽  
Vitalii Burnashev ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Change ◽  
Control Systems ◽  
Deep Sea ◽  
Phase Change Materials ◽  
High Pressures ◽  
Electric Heating ◽  
Control Module ◽  
Flexible Material ◽  
Buoyancy Control

Due to the extremely high pressures in the deep sea, heavy ballast tanks and pressure compensating hydraulic tanks are typically required to support the operation of classic buoyancy controls. Buoyancy control systems driven by phase-change materials (PCM) have unique advantages over conventional hydraulically actuated buoyancy control systems, including high adaptability for deep-sea exploration and simple, lightweight, and compact structures. Inspired by this, a buoyancy control module (BCM) was designed with flexible material as the shell. Instead of a conventional mechanical system, the device uses an electric heating drive to control buoyancy by heating and cooling the PCM. Based on the principle of pressure compensation, this device can adjust the buoyancy of a small underwater vehicle in a deep-sea high-pressure environment. The BCM successfully adjusts the buoyancy to lift itself up and down in the South China Sea at a depth of 3223 m. The performance of the phase-change BCM to control buoyancy under high pressure is validated by systematic experiments and theoretical analysis. Our work proposes a flexible scheme for the design of a deep-sea phase-change-driven BCM and highlights its potential application in deep-sea micro-mechanical systems, especially soft robots.

Monounsaturated but Not Polyunsaturated Fatty Acids Are Required for Growth of the Deep-Sea BacteriumPhotobacterium profundum SS9 at High Pressure and Low Temperature

1999 ◽  
Vol 65 (4) ◽  
pp. 1710-1720 ◽  
Author(s):  
Eric E. Allen ◽  
Daniel Facciotti ◽  
Douglas H. Bartlett
Keyword(s):  
Fatty Acids ◽  
High Pressure ◽  
Fatty Acid ◽  
Low Temperature ◽  
Mutant Strain ◽  
Deep Sea ◽  
High Pressures ◽  
Unsaturated Fatty Acids ◽  
Temperature Sensitive ◽  
Pressure Sensitive

ABSTRACT There is considerable evidence correlating the production of increased proportions of membrane unsaturated fatty acids (UFAs) with bacterial growth at low temperatures or high pressures. In order to assess the importance of UFAs to microbial growth under these conditions, the effects of conditions altering UFA levels in the psychrotolerant piezophilic deep-sea bacterium Photobacterium profundum SS9 were investigated. The fatty acids produced byP. profundum SS9 grown at various temperatures and pressures were characterized, and differences in fatty acid composition as a function of phase growth, and between inner and outer membranes, were noted. P. profundum SS9 was found to exhibit enhanced proportions of both monounsaturated (MUFAs) and polyunsaturated (PUFAs) fatty acids when grown at a decreased temperature or elevated pressure. Treatment of cells with cerulenin inhibited MUFA but not PUFA synthesis and led to a decreased growth rate and yield at low temperature and high pressure. In addition, oleic acid-auxotrophic mutants were isolated. One of these mutants, strain EA3, was deficient in the production of MUFAs and was both low-temperature sensitive and high-pressure sensitive in the absence of exogenous 18:1 fatty acid. Another mutant, strain EA2, produced little MUFA but elevated levels of the PUFA species eicosapentaenoic acid (EPA; 20:5n-3). This mutant grew slowly but was not low-temperature sensitive or high-pressure sensitive. Finally, reverse genetics was employed to construct a mutant unable to produce EPA. This mutant, strain EA10, was also not low-temperature sensitive or high-pressure sensitive. The significance of these results to the understanding of the role of UFAs in growth under low-temperature or high-pressure conditions is discussed.

Supercritical Impregnation of Organic Phase Change Materials into Polyester Fiber

2007 ◽  
Vol 544-545 ◽  
pp. 853-856
Author(s):  
Chang Sik Ju ◽  
Tae Won Kim ◽  
Si Young Kim
Keyword(s):  
High Pressure ◽  
Phase Change ◽  
Organic Phase ◽  
Phase Change Materials ◽  
High Energy ◽  
Polyester Fiber ◽  
High Pressure Pump ◽  
Supercritical Impregnation ◽  
A New Technique ◽  
Paraffin Waxes

A new technique preparing polyester fiber impregnated with organic phase change material(PCM) was proposed and experimentally examined. The impregnation apparatus consisted of a high pressure pump, two consecutive high pressure cylinders and auxiliary facilities. Polyester fiber was bound on cylindrical stainless steel net inside equilibrium cylinder and was impregnated with supercritical solution of PCM. PCMs, paraffin waxes and organic acids, were successfully impregnated into the polyester fiber even at temperature below it’s glass transition temperature(Tg), and the impregnated fibers showed high energy storage and release capacity around the melting point of respective PCMs.

scholarly journals PHASE CHANGE MATERIALS (PCM) FOR THERMAL CONTROL DURING SPACECRAFT TRANSPORTATION

2014 ◽  
pp. 235-239
Author(s):  
ARUN KUMAR. S ◽  
A. SEKAR ◽  
D.N.SIDDHARTHA JAIN ◽  
K.V. GOVINDA
Keyword(s):  
Phase Change ◽  
Control Systems ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Thermal Control ◽  
Control Architecture ◽  
Zero Temperature ◽  
Latent Heat Storage ◽  
Duty Cycles ◽  
Spacecraft Thermal Control

Phase Change materials (PCMs) absorb and release latent heat during their phase transition nearly at constant temperature. The latent heat storage phenomena using PCMs provides much higher storage density, with a smaller or zero temperature difference while storing and releasing of heat. PCMs have 5-14 times more heat capacity per unit volume than sensible storage materials that merits their usage as passive thermal control systems. They are effectively complemented with active thermal control systems in order to minimize their duty cycles and optimize the capacity. This paper discusses a passive thermal control system using PCMs to maintain the temperature within the limits inside the enclosures used for transportation of spacecrafts. Further, various applications of PCMs in the thermal control architecture as applied to spacecrafts are also discussed. The paper also discusses about the technologies such as Onboard power generation, Universal Spacecraft thermal control architecture and other significant spacecraft applications.

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.

Study on the Simulation of Electric Heating Phase Change Floor System

2011 ◽  
Vol 374-377 ◽  
pp. 263-267
Author(s):  
Jian Li ◽  
Jia Peng He
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Electric Heating ◽  
Heating System ◽  
Temperature Changes ◽  
Common System ◽  
The Common ◽  
Materials Used ◽  
The Stability ◽  
Floor System

Establishing a kind of electric heating system of phase change floor, analysing the stability and comfort through the simulation. Choosing the phase change materials, which the phase transition temperature is 29°C and the latent heat is 188 kJ/kg. The phase change materials used in electric heating floor heating system, comparing the general electric heating floor system, Calculating the floor surface temperature and indoor air temperature. It turned out that the heat storage of phase change floor system will be well, when compared to the common system, indoor temperature changes gently, human comfort higher. Phase change materials stores the cheap electricalheatenergy, and releases during daytime, So as to realize energy conservation and economy .

High-pressure Raman spectroscopy of phase change materials

2013 ◽  
Vol 103 (19) ◽  
pp. 191908 ◽  
Author(s):  
Wen-Pin Hsieh ◽  
Peter Zalden ◽  
Matthias Wuttig ◽  
Aaron M. Lindenberg ◽  
Wendy L. Mao
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Phase Change ◽  
Phase Change Materials

scholarly journals Large-Scale Transposon Mutagenesis of Photobacterium profundum SS9 Reveals New Genetic Loci Important for Growth at Low Temperature and High Pressure

2007 ◽  
Vol 190 (5) ◽  
pp. 1699-1709 ◽  
Author(s):  
Federico M. Lauro ◽  
Khiem Tran ◽  
Alessandro Vezzi ◽  
Nicola Vitulo ◽  
Giorgio Valle ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Deep Sea ◽  
Large Scale ◽  
High Pressures ◽  
Cell Envelope ◽  
Transposon Mutagenesis ◽  
Chromosomal Structure ◽  
And Function ◽  
Photobacterium Profundum

ABSTRACT Microorganisms adapted to piezopsychrophilic growth dominate the majority of the biosphere that is at relatively constant low temperatures and high pressures, but the genetic bases for the adaptations are largely unknown. Here we report the use of transposon mutagenesis with the deep-sea bacterium Photobacterium profundum strain SS9 to isolate dozens of mutant strains whose growth is impaired at low temperature and/or whose growth is altered as a function of hydrostatic pressure. In many cases the gene mutation-growth phenotype relationship was verified by complementation analysis. The largest fraction of loci associated with temperature sensitivity were involved in the biosynthesis of the cell envelope, in particular the biosynthesis of extracellular polysaccharide. The largest fraction of loci associated with pressure sensitivity were involved in chromosomal structure and function. Genes for ribosome assembly and function were found to be important for both low-temperature and high-pressure growth. Likewise, both adaptation to temperature and adaptation to pressure were affected by mutations in a number of sensory and regulatory loci, suggesting the importance of signal transduction mechanisms in adaptation to either physical parameter. These analyses were the first global analyses of genes conditionally required for low-temperature or high-pressure growth in a deep-sea microorganism.

Analysis of Heat Transfer Performance for Deepwater Phase Change Material Sandwich Pipes

2019 ◽  
Author(s):  
Chen An ◽  
Hui Wang ◽  
Menglan Duan
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Phase Change ◽  
Phase Change Material ◽  
Deep Sea ◽  
Phase Change Materials ◽  
Insulation Material ◽  
Insulation Layer ◽  
Radial Temperature ◽  
Change Material

Abstract As the exploitation of oil and gas gradually enters the deep sea, the low-temperature and high-pressure deep-sea environment poses a huge challenge to the flow protection of pipelines (2014a). In this paper, the phase change material sandwich pipeline which uses phase change heat storage and exothermic to maintain the pipeline temperature is taken as the research object, the heat transfer characteristics of the deep-water phase change material sandwich pipe are studied through the combination of theoretical analysis and numerical simulation (2014b). The main contents include: Firstly, through the establishment of two-dimensional and three-dimensional pipe models, analyzed the temperature distribution along the pipeline and the radial temperature distribution of the pipeline under steady oil flow conditions. Secondly, by using transient heat transfer, the effects of phase change material parameters, the proportion of phase change material in the insulation layer, and the difference in the ratio of phase change materials in the insulation layer on the insulation performance are analyzed to obtain the best results. Insulation material and optimal insulation layer layout; finally, the thermal storage and the phase change conditions of the phase-change material sandwich pipe is studied under the re-starting condition. The results show that the effective holding time of the phase change material insulation layer is close to 1.4 times that the non-phase change material insulation layer, and the melting point size has little effect on the insulation material. The closer the phase change material is to the inner tube, the better the insulation effect. This study provide guidance for the design and utilization of phase change material sandwich pipe.

Very High Pressure Generation at the Deep Sea

1983 ◽  
Vol 22 ◽  
Author(s):  
Kaichi Suito ◽  
Katsumi Yasukawa
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Natural Resources ◽  
Deep Sea ◽  
High Pressures ◽  
Large Area ◽  
High Pressure Apparatus ◽  
Very High

ABSTRACTIn the deep sea, truely hydrostatic pressure is produced in a very large area. This pressure may be used as natural resources. By utilizing these resources, very high pressures can be generated using a 6–8 type split-sphere high pressure apparatus. A preliminary experiment to generate very high pressure was undertaken in the deep sea at a depth of about 1000 m. Pressures of about 8.5 GPa were generated in the central part of the high pressure apparatus.

Crystallization fractionation technology for paraffin-based phase change materials production

2020 ◽  
pp. 33-38
Author(s):  
S.S. Kruglov (Jr.) ◽  
◽  
G.L. Patashnikov ◽  
S.S. Kruglov (Sr.) ◽  
◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials
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