scholarly journals Chart for Thermoelectric Systems Operation Based on a Ternary Diagram for Bithermal Systems

Entropy ◽  
2018 ◽  
Vol 20 (9) ◽  
pp. 666
Author(s):  
Julien Ramousse ◽  
Christophe Goupil
Keyword(s):  
Heat Pump ◽  
Heat Engine ◽  
Ternary Diagram ◽  
Operating Conditions ◽  
Thermal Dissipation ◽  
Maximum Efficiency ◽  
Joule Effect ◽  
Parametric Curve ◽  
Thermoelectric Systems ◽  
The Impact

Thermoelectric system’s operation needs careful attention to ensure optimal power conversion depending on the application aims. As a ternary diagram of bithermal systems allows a synthetic graphical analysis of the performance attainable by any work-heat conversion system, thermoelectric systems operation is plotted as a parametric curve function of the operating conditions (electric current and reservoirs’ temperature), based on the standard model of Ioffe. The threshold of each operating mode (heat engine, heat pump, thermal dissipation, and forced thermal transfer), along with the optimal efficiencies and powers of the heat pump and heat engine modes, are characterized graphically and analytically as a function of the material properties and the operating conditions. The sensibility of the performance aims (maximum efficiency vs. maximum power) with the operating conditions is, thus, highlighted. In addition, the specific contributions of each phenomenon involved in the semiconductor (reversible Seebeck effect, irreversible heat leakage by conduction and irreversible thermal dissipation by Joule effect) are discussed in terms of entropy generation. Finally, the impact of the exo-irreversibilities on the performance is analyzed by taking the external thermal resistances into account.

The Role of Internal Irreversibilities in the Performance and Stability of Power Plant Models Working at Maximum ϵ-Ecological Function

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gabriel Valencia-Ortega ◽  
Sergio Levario-Medina ◽  
Marco Antonio Barranco-Jiménez
Keyword(s):  
Power Plants ◽  
Heat Engine ◽  
Combined Cycle ◽  
Ecological Function ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Engine Model ◽  
Improved Stability ◽  
The Stability

Abstract The proposal of models that account for the irreversibilities within the core engine has been the topic of interest to quantify the useful energy available during its conversion. In this work, we analyze the energetic optimization and stability (local and global) of three power plants, nuclear, combined-cycle, and simple-cycle ones, by means of the Curzon–Ahlborn heat engine model which considers a linear heat transfer law. The internal irreversibilities of the working fluid measured through the r-parameter are associated with the so-called “uncompensated Clausius heat.” In addition, the generalization of the ecological function is used to find operating conditions in three different zones, which allows to carry out a numerical analysis focused on the stability of power plants in each operation zone. We noted that not all power plants reveal stability in all the operation zones when irreversibilities are considered through the r-parameter on real-world power plants. However, an improved stability is shown in the zone limited by the maximum power output and maximum efficiency regimes.

CFD Modelling of an Electrically Trace Heated Blanket

2019 ◽  
Author(s):  
Vincent Le Toux ◽  
Stéphanie Harchambois ◽  
Geoffrey Guindeuil ◽  
Romain Vivet ◽  
François-Xavier Pasquet ◽  
...  
Keyword(s):  
Natural Convection ◽  
Full Scale ◽  
Operating Conditions ◽  
Burial Depth ◽  
Test Results ◽  
Cfd Modelling ◽  
Joule Effect ◽  
Hydrate Dissociation ◽  
Cfd Models ◽  
The Impact

Abstract The Electrically Trace Heated Blanket (ETH-Blanket) is a new offshore intervention/remediation system currently in development by TechnipFMC for the efficient remediation of plugs due to hydrates or wax in subsea production and injection flowlines. The ETH-Blanket consists of a network of heating cables placed underneath an insulation layer which is laid onto the seabed above the plugged flowline. By applying electrical power to the cables, heat is generated by Joule effect which warms up the flowline content until hydrate dissociation or wax plug remediation through softening or complete melting. As part of a Joint Industry Project (JIP) between TechnipFMC, Shell and Total, full-scale thermal testing of an ETH-Blanket prototype was carried out in Artelia facilities (Grenoble, France). This testing was performed to verify the capability of the ETH-Blanket system to increase the temperature of the fluid inside a pipe sample above a target temperature (hydrate dissociation temperature or wax disappearance temperature) for various conditions. The impact of lateral misalignment of the ETH-blanket on the pipe and of the pipe burial depth were studied. Moreover, the tests were carried out on two pipe samples, with different designs and insulation properties. CFD models of the test set-up have been built to replicate the thermal behaviour of the ETH-Blanket prototype. Once validated against the test results, the final aim of CFD modelling is to be able to calculate the performances of the system in real subsea conditions. The modelling of the prototype includes a 3D geometry of the system including the soil, natural convection of water between the ETH-blanket and the pipe sample and natural convection of fluid in the pipe sample. The present paper focuses on the CFD work performed to match the full-scale thermal test results and to predict the ETH-Blanket performances for real subsea operating conditions. It will describe the various CFD models used, the sensitivities and findings in terms of local and global heat transfer and flow effects and the comparison to the experimental data.

scholarly journals Impact of Compressor Drive System Efficiency on Air Source Heat Pump Performance for Heating Hot Water

2020 ◽  
Vol 12 (24) ◽  
pp. 10521
Author(s):  
Mariusz Szreder ◽  
Marek Miara
Keyword(s):  
Heat Pump ◽  
Air Temperature ◽  
Heating System ◽  
Operating Conditions ◽  
Drive System ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Air Source Heat Pump ◽  
Heating Capacity ◽  
The Impact

A standard Polish household with a central heating system powered by a solid fuel furnace was chosen as a case study. The modular Air Source Heat Pump (ASHP) was used to heat the hot water outside the heating season. In this article comparative studies of the impact of the compressor drive system used on the energy efficiency of the heat pump have been carried out in operating conditions. The ASHP heating capacity and coefficient of performance (COP) were determined for the outside air temperature in the range from 7 to 22 °C by heating the water in the tank to a temperature above 50 °C. For the case of a fixed speed compressor, average heating capacity in the range 2.7−3.1 kW and COP values in the range 3.2−4.6 depending on the evaporator supply air temperature were obtained. Similarly, for the inverter compressor, the average heating capacity in the range of 2.7−5.1 kW was obtained for the frequency in the range of 30–90 Hz and COP in the range 4.2−5.7, respectively. On cool days, the average heating capacity of the heat pump decreases by 12%. For the simultaneous operation of two compressors with comparable heating capacity, lower COP values were obtained by 20%.

Development of Ammonia-Water Absorption Heat Pump Water Heater for Residential and Commercial Applications

2013 ◽  
Author(s):  
Michael Garrabrant ◽  
Roger Stout ◽  
Paul Glanville ◽  
Chris Keinath ◽  
Srinivas Garimella
Keyword(s):  
Natural Gas ◽  
Heat Pump ◽  
Operating Conditions ◽  
System Level ◽  
Outer Diameter ◽  
Water Heater ◽  
Absorption Heat Pump ◽  
Water Heaters ◽  
Commercial Applications ◽  
The Impact

Approximately half of the water heaters sold in the U.S. and Canada for residential and small commercial applications are natural gas fired storage water heaters, with a maximum theoretical thermal efficiency of 96%. A packaged water heater heated by a 2.9 kW absorption heat pump was designed and demonstrated in this study to achieve performance exceeding these limitations. The modeling and validation of the absorption cycle and of the natural gas-fired combustion system are discussed here. Heat transfer characteristics of the absorption components at expected operating conditions were used to model cycle performance. A single-effect system based on these models was fabricated and yielded a cyclic COP of 1.63, within 3% of predictions. A corresponding GAX cycle-based system yielded performance 20% lower than predicted values, indicating the need for larger heat and mass exchangers to achieve the expected system level performance. The gas-fired burner configuration required for this heat pump is governed by the water heater envelope, desorber geometry and process requirements, coupled with emissions requirements. Parametric CFD analyses were conducted to estimate the impact of chamber design on burner performance, and revealed a beneficial recirculation pattern within the combustion chamber that was strongly influenced by chamber height. Emission reductions depended on chamber diameter, and prototype burners with smaller outer diameter fabricated based on these designs met emission targets.

Performance Improvement of a Thermoacoustic Stirling Engine with In-Line Phase-Adjuster

2021 ◽  
pp. 1-14
Author(s):  
Isares Dhuchakallaya ◽  
Patcharin Saechan
Keyword(s):  
Acoustic Field ◽  
Acoustic Impedance ◽  
Heat Engine ◽  
Acoustic Power ◽  
Energy Conversion Efficiency ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Experimental Investigations ◽  
Set Up ◽  
High Level

Abstract This study examined the influence of an in-line phase-adjuster on the energy conversion efficiency of thermoacoustic Stirling heat engine (TASHE). The numerical and experimental investigations were performed. An acoustic field in the system can be adjusted by the phase-adjuster. Therefore, the TASHE could maintain high-level performance at all operating conditions. The phase-adjuster or the telescopic in-line piston was set up at the tail of the resonance tube. The TASHE was modeled by DeltaEC to search the optimal configurations. Due to the variations of acoustic loads or operating conditions from the design criteria, the engine absolutely cannot maintain maximum efficiency. The proposed phase-adjuster could bring back its maximum efficiency by re-matching the acoustic impedance in the regenerator. In the experiments, the self-excited and steady-state temperatures were 480°C and 397°C. The TASHE can provide an acoustic power of up to 40 W. The thermo-to-acoustic efficiency of 12.03%, related to 22.56% of the Carnot efficiency, was achieved. There was a reasonably good agreement between the measured and simulation results. The function of the phase-adjuster in tuning the acoustic impedance was demonstrated experimentally. In the case of the TASHE operated under the off-design conditions, these scenarios would drop the system efficiency. This research can confirm that the phase-adjuster is the component applied to tune the acoustic field in the regenerator accurately with the minimum changes. It could help to improve the efficiency of such consequences.

STUDY OF SPLIT-SYSTEM IN HEATING MODE

2015 ◽  
Vol 5 (1) ◽  
pp. 90-99
Author(s):  
Alinya O. KARTASHOVA ◽  
Daria O. KORTYAEVA ◽  
Ksenia E. KULYASOVA ◽  
Anna A. TSYNAEVA
Keyword(s):  
Heat Pump ◽  
Indoor Environment ◽  
Heating System ◽  
Operating Conditions ◽  
Mode Analysis ◽  
Working Fluid ◽  
Heating Mode ◽  
The Impact ◽  
System Operating ◽  
Split System

In this article there is a study of the heat pump for heating the premises of a public building (academic building of Samara State University of Architecture and Civil Engineering). The aim of the work was to determine the parameters of the heat pump and the impact of his work on the microclimate parameters of heated space. As the heat pump was activated split-system, operating in the heating mode; analysis was performed changing the state of the working fluid (Freon-R410A) used in this split-system. The studies revealed that the use of the heat pump (split system, operating in heating mode) allows you to maintain optimum parameters of the indoor environment. With the help of the tests revealed that the use of split-system as a heating system reduces the inertia of the system to ensure the indoor environment. This leads to maintain a comfortable environment for human habitation when the external operating conditions typical of the autumn-spring period, and demonstrates the effectiveness of the use of split systems, the use of which may in residential and public buildings. Furthermore, was prepared a graph of the room temperature before and after the operation of a split system.

Truck Tire Operating Temperatures on Flat and Curved Test Surfaces

2005 ◽  
Vol 33 (3) ◽  
pp. 156-178 ◽  
Author(s):  
T. J. LaClair ◽  
C. Zarak
Keyword(s):  
Flat Surface ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Load Pressure ◽  
Truck Tire ◽  
Endurance Testing ◽  
Operating Temperatures ◽  
The Impact ◽  
Tread Rubber ◽  
Cylindrical Test

Abstract Operating temperature is critical to the endurance life of a tire. Fundamental differences between operations of a tire on a flat surface, as experienced in normal highway use, and on a cylindrical test drum may result in a substantially higher tire temperature in the latter case. Nonetheless, cylindrical road wheels are widely used in the industry for tire endurance testing. This paper discusses the important effects of surface curvature on truck tire endurance testing and highlights the impact that curvature has on tire operating temperature. Temperature measurements made during testing on flat and curved surfaces under a range of load, pressure and speed conditions are presented. New tires and re-treaded tires of the same casing construction were evaluated to determine the effect that the tread rubber and pattern have on operating temperatures on the flat and curved test surfaces. The results of this study are used to suggest conditions on a road wheel that provide highway-equivalent operating conditions for truck tire endurance testing.

A NEW WELDING MATERIAL FOR REGENERATION IN THE WELDING TECHNOLOGY BASED ON NICKEL. ANALYSIS OF THE COMPOSITION AND PROPERTIES OF DEFORMABLE HEAT-RESISTANT HIGH-CHROMIUM NICKEL-BASED ALLOYS FOR WELDED PARTS. ANALYSIS OF EXISTING FUELLING STATIONS TYPES AND VEHICLES USING HYDROGEN, HYDROGEN PRODUCTION AND STORING METHODS

2019 ◽  
pp. 43-48
Author(s):  
Ben Nengjun ◽  
Zhou Pengfei ◽  
Oleksandr Labartkava ◽  
Mykhailo Samokhin
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Nickel Alloys ◽  
Total Content ◽  
Operating Conditions ◽  
High Temperature Strength ◽  
High Chromium ◽  
Salt Corrosion ◽  
Tcp Phases ◽  
The Impact

This work involves an analysis of high-chromium high-temperature deformable wieldable nickel alloys for use in GTE repair assemblies. It is shown that the alloys EP868 (VZh98) and Haynes 230 can be used in welded assemblies with an operating temperature of 800-1100 °C. The alloys Nimonic 81, Nimonic 91, IN 935, IN 939, and Nicrotan 2100 GT also have a high potential for use in welded assemblies. They are characterized by a combination of good weldability, high-temperature strength, and resistance to scaling. There have been conducted studies on high-temperature salt corrosion of model nickel alloys. They allowed establishing the patterns of the impact of base metal alloying with chromium, aluminum, titanium, cobalt, tungsten, molybdenum, niobium, tantalum and rare earth metals on the critical temperature of the start of salt corrosion Tcor and the alloy mass loss. It has been established that alloys with a moderate concentration (13-16%) of chromium can possess satisfactory hightemperature corrosion resistance (HTC resistance) under the operating conditions of ship GTE. The HTC resistance of CrAl-Ti alloys improves upon reaching the ratio Ti/Al ˃ 1. Meanwhile, the ratio Ti/Al ˂ 1 promotes the formation of corrosion products with low protective properties. The positive effect of tantalum on the HTC resistance of alloys is manifested at higher test temperatures than that of titanium, and the total content of molybdenum and tungsten in alloys is limited by the condition 8Mo2 – 2W2 = 89. The presence of refractory elements stabilizes the strengthening phase and prevents formation of the ɳ-phase. However, their excess promotes formation of the embrittling topologically close packed (TCP) phases and boundary carbides of an unfavorable morphology. Based on the studies of the HTC resistance, there has been identified a class of model high-temperature corrosionresistant nickel alloys with a moderate or high chromium content (30%), Ti/Al ˃ 1, and a balanced content of refractory and rare-earth elements.

Application of vacuum belt press filters for cane mud filtration and performance comparison with rotary filters

2014 ◽  
pp. 298-301 ◽  
Author(s):  
Arnaud Petit
Keyword(s):  
Electricity Consumption ◽  
Performance Comparison ◽  
Operating Conditions ◽  
Vacuum Filter ◽  
Sugar Mill ◽  
Belt Press ◽  
Vacuum Belt ◽  
And Performance ◽  
Mud Filtration ◽  
The Impact

Bois-Rouge factory, an 8000 t/d cane Reunionese sugarcane mill, has fully equipped its filtration station with vacuum belt press filters since 2010, the first one being installed in 2009. The present study deals with this 3-year experience and discusses operating conditions, electricity consumption, performance and optimisation. The comparison with the more classical rotary drum vacuum filter station of Le Gol sugar mill highlights advantages of vacuum belt press filters: high filtration efficiency, low filter cake mass and sucrose content, low total solids content in filtrate and low power consumption. However, this technology needs a mud conditioning step and requires a large amount of water to improve mud quality, mixing of flocculant and washing of filter belts. The impact on the energy balance of the sugar mill is significant. At Bois-Rouge mill, studies are underway to reduce the water consumption by recycling low d.s. filtrate and by dry cleaning the filter belts.

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