scholarly journals Zeolite NaY-Copper Composites Produced by Sintering Processes for Adsorption Heat Transformation—Technology, Structure and Performance

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1958
Author(s):  
Andreas Velte ◽  
Jörg Weise ◽  
Eric Laurenz ◽  
Joachim Baumeister ◽  
Gerrit Füldner
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Metal Structure ◽  
Heat Pumps ◽  
Adsorption Heat ◽  
Thermal Mass ◽  
Heat Conducting ◽  
Zeolite Nay ◽  
Heat Transformation ◽  
The Impact

In adsorption heat pumps, the adsorbent is typically combined with heat conducting structures in order to ensure high power output. A new approach for the direct integration of zeolite granules into a copper structure made of short copper fibers is presented here. Zeolite NaY granules with two different grain sizes are coated with copper fibers and powder and sintered to larger structures. The sorption dynamics of these structures were measured and evaluated in terms of heat and mass transfer resistances and compared to the loose grain configuration of the same material. We found that the thermal conductivity of such a composite structure is approximately 10 times higher than the thermal conductivity of an adsorbent bed with NaY granules. Sorption equilibrium measurements with a volumetric method indicate that the maximum uptake is not altered by the manufacturing process. Furthermore, the impact of the adsorbent–metal structure on the total thermal mass of an adsorption heat exchanger is evaluated. The price of the superior thermal conductivity is a 40% higher thermal mass of the adsorption heat exchanger compared to the loose grain configuration.

scholarly journals Experimentally Measured Thermal Masses of Adsorption Heat Exchangers

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1150 ◽  
Author(s):  
Kyle R. Gluesenkamp ◽  
Andrea Frazzica ◽  
Andreas Velte ◽  
Steven Metcalf ◽  
Zhiyao Yang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pumps ◽  
Adsorption Heat ◽  
Heat Transfer Fluid ◽  
Thermal Mass ◽  
Detailed Calculation ◽  
Adsorption Heat Pump ◽  
Reported Data ◽  
Future Work ◽  
The Impact

The thermal masses of components influence the performance of many adsorption heat pump systems. However, typically when experimental adsorption systems are reported, data on thermal mass are missing or incomplete. This work provides original measurements of the thermal masses for experimental sorption heat exchanger hardware. Much of this hardware was previously reported in the literature, but without detailed thermal mass data. The data reported in this work are the first values reported in the literature to thoroughly account for all thermal masses, including heat transfer fluid. The impact of thermal mass on system performance is also discussed, with detailed calculation left for future work. The degree to which heat transfer fluid contributes to overall effective thermal mass is also discussed, with detailed calculation left for future work. This work provides a framework for future reporting of experimental thermal masses. The utilization of this framework will enrich the data available for model validation and provide a more thorough accounting of adsorption heat pumps.

Characteristics of Flame Bases for V-Gutters Stabilized Premixed Flames

2013 ◽  
Author(s):  
Fan Gong ◽  
Yong Huang
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Heat Conducting ◽  
Inlet Velocity ◽  
The Impact

The objective of this work is to investigate the flame stabilization mechanism and the impact of the operating conditions on the characteristics of the steady, lean premixed flames. It’s well known that the flame base is very important to the existence of a flame, such as the flame after a V-gutter, which is typically used in ramjet and turbojet or turbofan afterburners and laboratory experiments. We performed two-dimensional simulations of turbulent premixed flames anchored downstream of the heat-conducting V-gutters in a confined passage for kerosene-air combustion. The flame bases are symmetrically located in the shear layers of the recirculation zone immediately after the V-gutter’s trailing edge. The effects of equivalence ratio of inlet mixture, inlet temperature, V-gutter’s thermal conductivity and inlet velocity on the flame base movements are investigated. When the equivalence ratio is raised, the flame base moves upstream slightly and the temperature gradient dT/dx near the flame base increases, so the flame base is strengthened. When the inlet temperature is raised, the flame base moves upstream very slightly, and near the flame base dT/dx increases and dT/dy decreases, so the flame base is strengthened. As the V-gutter’s thermal conductivity increases, the flame base moves downstream, and the temperature gradient dT/dx near the flame base decreases, so the flame base is weakened. When the inlet velocity is raised, the flame base moves upstream, and the convection heat loss with inlet mixture increases, so the flame base is weakened.

scholarly journals Establishing patterns in the effect of temperature regime when manufacturing nanocomposites on their heat-conducting properties

2021 ◽  
Vol 4 (5(112)) ◽  
pp. 21-26
Author(s):  
Nataliia Fialko ◽  
Roman Dinzhos ◽  
Julii Sherenkovskii ◽  
Nataliia Meranova ◽  
Diana Izvorska ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Regime ◽  
Main Parameter ◽  
Polymer Melt ◽  
Effect Of Temperature ◽  
Heat Conducting ◽  
Composite Manufacturing ◽  
Energy Saving Technology ◽  
Percolation Thresholds ◽  
The Impact

This paper reports the experimental study carried out to establish the dependence of the thermal conductivity of polypropylene-based nanocomposites filled with carbon nanotubes on the main parameter of the temperature regime of their manufacturing ‒ the level of overheating a polymer melt relative to its melting point. The study has been conducted for nanocomposites that were manufactured by applying a method based on the mixing of components in the polymer melt applying a special disk extruder. During the composite manufacturing process, the level of melt overheating varied from 10 to 75 K, with the mass share of filler ranging from 0.3 to 10.0 %. It is shown that increasing the overheating of a polymer melt causes an increase in the thermal conductivity of the composites. However, when the overheating has reached a certain value, its further growth does not increase the thermal conductivity of nanocomposites. Based on the established pattern, the rational level of this overheating has been determined. That resolves the tasks of manufacturing highly heat-conducting nanocomposites and implementing appropriate energy-saving technology. Data have been acquired on the effects of the impact of the amount of polymer melt overheating on the values of the first and second percolation thresholds for the examined nanocomposites. It is established that the value of the first percolation threshold is more sensitive to the specified amount of overheating. The dependences of the density of the examined composites on the level of polymer melt overheating have been derived. The correlation between a given dependence and the nature of a corresponding change in the thermal conductivity of the composites has been established. Applying the proposed highly heat-conducting nanocomposites is promising for micro and nanoelectronics, energy, etc.

scholarly journals Thermal performance of the ground in geothermal pavements

2020 ◽  
Vol 205 ◽  
pp. 06015
Author(s):  
Yaser Motamedi ◽  
Nikolas Makasis ◽  
Arul Arulrajah ◽  
Suksun Horpibulsuk ◽  
Guillermo Narsilio
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Thermal Response ◽  
Geothermal Heat ◽  
Capital Costs ◽  
Ground Source ◽  
Shallow Geothermal Energy ◽  
Novel Concept ◽  
Response Testing ◽  
The Impact

Shallow geothermal energy utilises the ground at relatively shallow depths as a heat source or sink to efficiently heat and cool buildings. Geothermal pavement systems represent a novel concept where horizontal ground source heat pump systems (GSHP) are implemented in pavements instead of purpose-built trenches, thus reducing their capital costs. This paper presents a geothermal pavement system segment (20m × 10m) constructed and monitored in the city of Adelaide, Australia, as well as thermal response testing (TRT) results. Pipes have been installed in the pavement at 0.5 m depth, and several thermistors have been placed on the pipes and in the ground. A TRT has been performed with 6kW heating load to achieve an understanding of the thermal response of the system as well as to estimate the effective thermal conductivity of the ground. The results show that the conventional semi-log method may be applicable to determine the thermal conductivity for geothermal pavements. The geothermal heat exchanger at shallow depth is considerably under the influence of the ambient temperature; however, it is still acceptable for exchanging the heat within the ground. It is also concluded that the impact radius of heat exchanger in geothermal pavement during the TRT is around 0.5m in the vertical and horizontal directions for this case study.

DEVELOPMENT AND RESEARCH OF HIGH EFFICIENT FANS OF RECUPERATORS FOR DECENTRALIZED INSTALLATION IN RESIDENTIAL COMPLEXES

2017 ◽  
Vol 7 (4) ◽  
pp. 32-37
Author(s):  
Andrey G. MATVEEV
Keyword(s):  
Heat Exchanger ◽  
Heat Pipes ◽  
High Heat ◽  
Heat Pumps ◽  
Heat Conducting ◽  
Ongoing Research ◽  
Effi Ciency ◽  
High Efficient ◽  
Innovative Products

The article deals with the introduction of decentralized fans of recuperators of exhaust air heat, including using high-heat-conducting heat pipes with an intermediate coolant as a heat exchanger. The considered criteria form a comparative basis for the developed designs of heat recuperators for ventilation air in buildings, including heat pipes. The energy and economic effi ciency of such recuperators is analyzed. Areas are singled out where the use of heat recuperators is much more eff ective than increasing the capacity of heat pumps. As a result of ongoing research, cooling or heating modules based on aluminum, aluminum-copper radiators with integrated heat pipes will be developed as innovative products.

scholarly journals Electrocaloric devices part II: All-solid heat pump without moving parts

2020 ◽  
Vol 10 (06) ◽  
pp. 2050029
Author(s):  
Farrukh Najmi ◽  
Jianping He ◽  
Lorenzo Cremaschi ◽  
Z.-Y. Cheng
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Heat Conduction ◽  
Electric Fields ◽  
Heat Pumps ◽  
Source To Sink ◽  
Heat Transformation ◽  
Source Sink ◽  
Continuous Heat ◽  
Source And Sink

Various designs have been introduced to build heat pumps using the electrocaloric effect (ECE). Each of all the current designs uses at least one moving part, which significantly reduces the reliability of the pump and adds complexities. In this work, a new all-solid design is introduced, in which two layers of an electrocaloric material (ECM) are permanently sandwiched in the source and sink, which would significantly increase the device’s reliability since nothing moves and all are permanently bound together. More importantly, the electric fields applied on two ECM layers are independently controlled. A special sequence for the electric fields on two ECM layers is introduced. Numerical calculation was used to simulate the device’s performance by using the newly introduced analytical solutions for the heat conduction in the system. It is concluded that a continuous heat transformation from the source to sink at the same temperature can be achieved when the contacting coefficient, [Formula: see text], is very small, where [Formula: see text], [Formula: see text], and [Formula: see text] are thermal conductivity, density, and heat capacity, respectively, while the superscript [Formula: see text] and [Formula: see text] represent the ECM and source/sink, respectively.

scholarly journals The impact of filling level resolved: Capillary-assisted evaporation of water for adsorption heat pumps

2016 ◽  
Vol 102 ◽  
pp. 513-519 ◽  
Author(s):  
Franz Lanzerath ◽  
Jan Seiler ◽  
Meltem Erdogan ◽  
Heike Schreiber ◽  
Matthias Steinhilber ◽  
...  
Keyword(s):  
Heat Pumps ◽  
Adsorption Heat ◽  
The Impact

The Impact of Base Metal on the Thermal-Hydraulic Performance of Metal Foam Heat Exchanger for Cooling and Dehumidification Applications

2017 ◽  
Author(s):  
Kashif Nawaz ◽  
Anthony M. Jacobi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Exchanger ◽  
Base Metal ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Metal Foam ◽  
Operating Conditions ◽  
Copper Metal ◽  
The Impact

In the wake of utilization of novel materials in various thermal applications open cell metal foams have received attention due to their inherent properties such as large surface area to volume ratio and higher thermal conductivity. Additionally, complex tetradecahedron structure promotes mixing and makes them a good candidate for heat transfer applications. In this paper, a relative comparison has been made between the thermal-hydraulic performance of aluminum and copper metal foam heat exchangers with the same geometry under dry and wet operating conditions. Heat exchanger consisting of round tube with annular layer of metal foam have been considered. Experiments have been conducted using a closed-loop wind tunnel to measure the heat transfer performance and pressure drop. The impact of base metal (aluminum and copper) on the heat transfer rate has been evaluated at varying air flow rates and upstream relative humidity. It has been found that due to similar geometry (flow depth, face area, pore size) both aluminum and copper foam samples have comparable pressure drop under dry conditions. However, the pressure gradient was noticeably different for two samples under wet operating conditions. An obvious difference in heat transfer rate for aluminum and copper metal foam heat exchangers was observed under both dry and wet operating conditions. The findings have been explained in terms of the impact of the thermal conductivity of base metal and condensate retention.

Adsorber heat exchanger using Al-fumarate beads for heat-pump applications – a transport study

2021 ◽  
Author(s):  
David Farrusseng ◽  
Cécile Daniel ◽  
Conor Hamill ◽  
Jose Casaban ◽  
Terje Didriksen ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Water Adsorption ◽  
Heat Pumps ◽  
Adsorption Heat ◽  
Transport Study ◽  
Cost Efficient ◽  
Scalable Synthesis ◽  
The Cost

This paper describes the cost-efficient and scalable synthesis and shaping processes of Al(OH)-fumarate beads of various sizes appropriate for use in water Adsorption Heat-Pumps (AHPs).

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