scholarly journals Energy Benefits of Heat Pipe Technology for Achieving 100% Renewable Heating and Cooling for Fifth-Generation, Low-Temperature District Heating Systems

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5398
Author(s):  
Birol Kılkış ◽  
Malik Çağlar ◽  
Mert Şengül
Keyword(s):  
Low Temperature ◽  
Heat Pipe ◽  
Co2 Emissions ◽  
Low Temperatures ◽  
Heat Pipes ◽  
Paris Agreement ◽  
Heating Equipment ◽  
Heating Systems ◽  
Heating And Cooling ◽  
The Eu

This paper addresses the challenges the policymakers face concerning the EU decarbonization and total electrification roadmaps towards the Paris Agreement set forth to solve the global warming problem within the framework of a 100% renewable heating and cooling target. A new holistic model was developed based on the Rational Exergy Management Model (REMM). This model optimally solves the energy and exergy conflicts between the benefits of using widely available, low-temperature, low-exergy waste and renewable energy sources, like solar energy, and the inability of existing heating equipment, which requires higher exergy to cope with such low temperatures. In recognition of the challenges of retrofitting existing buildings in the EU stock, most of which are more than fifty years old, this study has developed a multi-pronged solution set. The first prong is the development of heating and cooling equipment with heat pipes that may be customized for supply temperatures as low as 35 °C in heating and as high as 17 °C in cooling, by which equipment oversizing is kept minimal, compared to standard equipment like conventional radiators or fan coils. It is shown that circulating pump capacity requirements are also minimized, leading to an overall reduction of CO2 emissions responsibility in terms of both direct, avoidable, and embodied terms. In this respect, a new heat pipe radiator prototype is presented, performance analyses are given, and the results are compared with a standard radiator. Comparative results show that such a new heat pipe radiator may be less than half of the weight of the conventional radiator, which needs to be oversized three times more to operate at 35 °C below the rated capacity. The application of heat pipes in renewable energy systems with the highest energy efficiency and exergy rationality establishes the second prong of the paper. A next-generation solar photo-voltaic-thermal (PVT) panel design is aimed to maximize the solar exergy utilization and minimize the exergy destruction taking place between the heating equipment. This solar panel design has an optimum power to heat ratio at low temperatures, perfectly fitting the heat pipe radiator demand. This design eliminates the onboard circulation pump, includes a phase-changing material (PCM) layer and thermoelectric generator (TEG) units for additional power generation, all sandwiched in a single panel. As a third prong, the paper introduces an optimum district sizing algorithm for minimum CO2 emissions responsibility for low-temperature heating systems by minimizing the exergy destructions. A solar prosumer house example is given addressing the three prongs with a heat pipe radiator system, next-generation solar PVT panels on the roof, and heat piped on-site thermal energy storage (TES). Results showed that total CO2 emissions responsibility is reduced by 96.8%. The results are discussed, aiming at recommendations, especially directed to policymakers, to satisfy the Paris Agreement.

A Numerical Analysis of Gas Turbine Disks Incorporating Rotating Heat Pipes

2000 ◽  
Author(s):  
Y. Cao ◽  
J. Ling ◽  
R. Rivir ◽  
C. MacArthur
Keyword(s):  
Heat Pipe ◽  
Gas Turbine ◽  
Heat Pipes ◽  
High Heat ◽  
Thermal Dissipation ◽  
High Heat Flux ◽  
Heating And Cooling ◽  
Turbine Disks ◽  
Higher Temperature ◽  
Lower Temperature

Abstract Radially rotating heat pipes have been proposed for cooling gas turbine disks working at high temperatures. A disk incorporating the heat pipe would have an enhanced thermal dissipation capacity and a much lower temperature at the disk rim and dovetail surface. In this paper, extensive numerical simulations have been made for heat-pipe-cooled disks. Thermal performances are compared for the disks with and without incorporating the heat pipe at different heating and cooling conditions. The numerical results presented in this paper indicate that radially rotating heat pipes can significantly reduce the maximum and average temperatures at the disk rim and dovetail surface under a high heat flux working condition. In general, the maximum and average temperatures at the disk rim and dovetail surface could be reduced by above 250 and 150 degrees, respectively, compared to those of the disk without the heat pipe. As a result, a disk incorporating radially rotating heat pipes could alleviate temperature-related problems and allow a gas turbine to work at a much higher temperature.

The Necessity of RTCVD in Advanced Epitaxial Growth of Si and SiGe

1995 ◽  
Vol 387 ◽  
Author(s):  
W. B. De Boer ◽  
M. J.J. Theunissen ◽  
R. H. J. Van Der Linden
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Gas Flows ◽  
Level Control ◽  
Reduced Pressure ◽  
Heating And Cooling ◽  
Present Generation ◽  
Low Temperature Epitaxy ◽  
Made In ◽  
Strained Sige

AbstractDevice-quality epi material can be grown at temperatures ranging from 600 to 800°C in commercially available production reactors. The exceptionally steep transitions of Ge, B and, to a lesser extent, P, are characteristics of Si and strained SiGe epi growth from dichlorosilane and germane in hydrogen ambient at atmospheric or reduced pressure. Although the growth rates depend on the dopant gas flows at low temperatures, layer thickness and doping level control is excellent. Selective multilayer growth at reduced pressure seems a viable process and can be applied in e.g. HBT's.In spite of the fact that a lot of the progress in low-temperature epitaxy has been made in lampheated reactors, it is argued that RTP is not needed for low-temperature epitaxy. This is in contrast to conventional (high-temperature) epitaxy where RTP is becoming indispensable. Real RTP, heating and cooling the wafer in just a couple of seconds, would improve the throughput of the present generation single wafer epi reactors tremendously and seems feasible.

Performance Characteristics of a Concentric Annular Heat Pipe: Part I—Experimental Prediction and Analysis of the Capillary Limit

1989 ◽  
Vol 111 (4) ◽  
pp. 844-850 ◽  
Author(s):  
A. Faghri ◽  
S. Thomas
Keyword(s):  
Heat Pipe ◽  
Unit Length ◽  
Heat Pipes ◽  
Simple Analysis ◽  
Cross Sectional ◽  
Heating And Cooling ◽  
Experimental Prediction ◽  
Capillary Limit ◽  
Heating Loads ◽  
Vapor Space

This paper describes the design, testing, and theoretical capillary limit prediction of a new heat pipe configuration, which is the concentric annular heat pipe. The concentric annular heat pipe is made of two concentric pipes of unequal diameters that create an annular vapor space. With this arrangement, capillary wicks can be placed on both the inside of the outer pipe and the outside of the inner pipe. This design significantly increases the heat capacity per unit length compared to conventional heat pipes, since the cross-sectional area of the wick as well as the surface area for heating and cooling are increased. The heat pipe was tested for the temperature distribution in the three sections of the heat pipe under various tilt angles and heating loads through the inner and outer pipes in the evaporator section. A simple analysis for the prediction of the capillary limitation of the concentric annular heat pipe is presented.

Investigation of thermal performance of double-layered thermally activated building system in heating mode

2021 ◽  
pp. 095440622199279
Author(s):  
Oğuzhan Çalişir ◽  
Müjdat Öztürk ◽  
Gamze Genç
Keyword(s):  
Thermal Performance ◽  
Low Temperatures ◽  
Renewable Energy Sources ◽  
Vertical Axis ◽  
Heating System ◽  
Coefficient Of Performance ◽  
Layered System ◽  
Heating Systems ◽  
Heating And Cooling ◽  
Building System

Main principle of the thermally active building system (TABS) which is a type of radiant heating system operating at low temperatures range as 30–50 ˚C is to bring the ambient temperature to the desired level by heating the building mass. TABS system is also a system that can heat at low temperatures such as underfloor heating systems, and both systems can be applied in multi-story buildings. Because these systems operate at low temperatures, they are compatible with both each other and with renewable energy sources. At the same time, heating and cooling at temperatures close to room temperature can also increase the coefficient of performance (COP) in these systems. In this study, a double-layered system which is a new concept was designed by using both underfloor heating and TABS on the same floor; and the thermal performance of the double-layered TABS system (DLTS) was examined using the FLUENT/ANSYS programs. In the calculations, different supply water temperatures (30, 35 and 40 °C) and the pipe positions on the vertical axis (0.001 m, 0.050 m, and 0.100 m) were considered. It can be obtained from the results that the efficiency of the heating systems can be increased by using the new DLTS proposed in this study.

scholarly journals Withering of tea leaves using heat pipe heat exchanger by utilizing low-temperature geothermal energy

2020 ◽  
Author(s):  
Yohanes Gunawan ◽  
Nandy Putra ◽  
Imansyah Ibnu Hakim ◽  
Dinni Agustina ◽  
Teuku Meurah Indra Mahlia
Keyword(s):  
Heat Exchanger ◽  
Low Temperature ◽  
Heat Pipe ◽  
Geothermal Energy ◽  
Outer Diameter ◽  
The European Union ◽  
Tea Leaves ◽  
Direct Use ◽  
Pipe Heat ◽  
The Eu

Abstract The volume of Indonesian tea exports to the European Union (EU) decreased by 43% in 2014 because of the EU setting a maximum residue limit of anthraquinone (AQ) for tea as 0.02 mg/kg. The content of AQ in tea leaves increases when there is incomplete combustion in the combustion of firewood for the energy source of withering and drying of tea leaves. This study aims to develop and test a new concept for the direct use of low-temperature geothermal energy with a heat pipe heat exchanger (HPHE) for the withering of tea leaves as a solution for energy sources free from AQ. The geothermal fluid simulators use water, which is heated by heater and flowed by a pump. The HPHE used consists of 42 heat pipes and 181 fins. The heat pipe used has a length of 700 mm with an outer diameter of 10 mm. Each fin is made of aluminum with a thickness of 0.105 mm and a size of 76 × 345 mm2. The results show that the effectiveness of the HPHE varies from 66% to 79.59%. For 100 g of fresh tea leaves, the heating energy produced ranges from 15.21 W to 45.07 W, meaning it can wither tea leaves from 80% (w.b.) to 54% (w.b.) in a variety of 11 h 56 min to only 49.6 min. The Page mathematical model is the best model to represent the behavior of the tea leaves with this HPHE system.

scholarly journals Theoretical analysis and experimental research of heat pump driving heat pipes heating equipment

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 1019-1029
Author(s):  
Ruochen Ding ◽  
Baorui Du ◽  
Shuxue Xu ◽  
Jun Yao ◽  
Huilong Zheng
Keyword(s):  
Heat Pipe ◽  
Heat Pump ◽  
Composite System ◽  
Working Condition ◽  
Heat Pipes ◽  
Design Parameters ◽  
Heating Equipment ◽  
Start Up ◽  
Heating Capacity ◽  
Operation Characteristics

In this study, the main design parameters of the heat pump/heat pipe composite system were calculated. The operation characteristics of the heat pump/heat pipe composite system under low temperature were experimentally studied. The start-up character of the heat pipe radiator and heat pipe radiator surface temperature distribution were obtained. The variation of heating capacity and heating coefficient of performaance of the heat pump/heat pipe composite system with different working condition was obtained. Experimental results show that the heat pump/heat pipe composite system can operate efficiently and steadily when the outdoor temperature is ?20~5?C, and meet the winter heating demand in cold areas.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

INVAR M93

Alloy Digest ◽  
2008 ◽  
Vol 57 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Bend Strength ◽  
Temperature Performance ◽  
Ni Content ◽  
Precision Alloys ◽  
Ni Alloy

Abstract Invar is an Fe-Ni alloy with 36% Ni content that exhibits the lowest expansion of known metals from very low temperatures up to approximately 230 deg C (445 deg F). Invar M93 is a cryogenic Invar with improved weldability. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear and bend strength as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as forming and joining. Filing Code: FE-143. Producer or source: Metalimphy Precision Alloys.

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