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    Wyświetlanie 1-13 z 13
    Tytuł:
    Modelling of back propagation neural network to predict the thermal performance of porous bed solar air heater
    Autorzy:
    Ghritlahre, Harish Kumar
    Prasad, Radha Krishna
    Powiązania:
    https://bibliotekanauki.pl/articles/240570.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    solar air heater
    porous bed
    thermal performance
    artificial neural network
    Levenberg-Marquardt algorithm
    Opis:
    The objective of present work is to predict the thermal performance of wire screen porous bed solar air heater using artificial neural network (ANN) technique. This paper also describes the experimental study of porous bed solar air heaters (SAH). Analysis has been performed for two types of porous bed solar air heaters: unidirectional flow and cross flow. The actual experimental data for thermal efficiency of these solar air heaters have been used for developing ANN model and trained with Levenberg-Marquardt (LM) learning algorithm. For an optimal topology the number of neurons in hidden layer is found thirteen (LM-13).The actual experimental values of thermal efficiency of porous bed solar air heaters have been compared with the ANN predicted values. The value of coefficient of determination of proposed network is found as 0.9994 and 0.9964 for unidirectional flow and cross flow types of collector respectively at LM-13. For unidirectional flow SAH, the values of root mean square error, mean absolute error and mean relative percentage error are found to be 0.16359, 0.104235 and 0.24676 respectively, whereas, for cross flow SAH, these values are 0.27693, 0.03428, and 0.36213 respectively. It is concluded that the ANN can be used as an appropriate method for the prediction of thermal performance of porous bed solar air heaters.
    Źródło:
    Archives of Thermodynamics; 2019, 40, 4; 103-128
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal performance evaluation of an earth-to-air heat exchanger for the heating mode applications using an experimental test rig
    Autorzy:
    Ahmad, Saif Nawaz
    Prakash, Om
    Powiązania:
    https://bibliotekanauki.pl/articles/2091363.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heat transfer
    earth-to-air heat exchanger
    ground heat exchanger
    geothermal energy
    renewable energy
    assive heating
    assive cooling
    effectiveness
    Opis:
    This paper presents the experimental investigation of an earth-to-air heat exchanger for heating purposes in the Patna region of India, using an experimental test rig. In the view of the author, real field experiments have several limitations such as lack of repeatability and uncontrolled conditions. It also takes more time for the response of parameters that depends on nature and climate. Moreover, earth-to-air heat exchangers may be expensive to fabricate and require more land area. Thus, in this work authors executed their experimental work in indoor controllable environments to investigate the thermal performance of an earth-to-air heat exchanger. The actual soil conditions were created and maintained the temperature at 26°C throughout the soil in the vicinity of pipes. Three horizontal PVC pipes of equal lengths and diameters of 0.0285 m, 0.038 m and 0.0485 m were installed in the test rig. The experiments were performed for different inlet air velocities at ambient air temperature. This study acknowledges that the maximum rise in outlet temperature occurs at a lower speed for smaller pipes. Also, the maximum effectiveness of 0.83 was observed at 2 m/s for the smallest diameter pipe.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 1; 185--207
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal efficiency and hydraulic performance evaluation on Ag–Al2O3 and SiC–Al2O3 hybrid nanofluid for circular jet impingement
    Autorzy:
    Datta, Abanti
    Halder, Pabitra
    Powiązania:
    https://bibliotekanauki.pl/articles/1845498.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    hybrid nanofluid
    thermal performance factor
    pumping power
    merit number
    Opis:
    Hybrid nanofluids is obtained by dispersing more than one nanoparticle into a base fluid. The work is concerned with a detailed numerical investigation of the thermal efficiency and hydraulic performance of hybrid nanofluids for circular jet impinges on a round plate. For this paper, a metal (Ag), a metal oxides (Al2O3) and a metal carbides (SiC) nanoparticle and their water based hybrid nanofluids are considered to analyse numerically with varying significant dimensionless parameters, i.e., the jet-to-plate spacing ratio, Reynolds number and volume fraction of nanoparticles. The results demonstrated that the efficiency of heat transfer of all nanofluids is increased by the addition of nanoparticle to the dispersed in water at constant Reynolds number. Moreover, the results illustrate that heat transfer efficacy and pumping power penalty both increased as jet-to-plate spacing ratio reduced. The jet-to-plate spacing ratio equal to 4 is the best as the percentage enhance heat transfer is maximum in this situation. Since both the heat transfer effect and pumping penalty increase using hybrid nanofluids, thermal performance factor increases or decreases depends on nanoparticles of nanofluids. It is evident that the analysis of these hybrid nanofluids will consider both the increase in heat efficiency and the pumping capacity. The best flow behaviour is achieved for SiC–Al2O3 hybrid nanofluids. New merit number is introduced for additional clarification.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 1; 163-182
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Solar air heater performance prediction using artificial neural network technique with relevant input variables
    Autorzy:
    Ghritlahre, Harish Kumar
    Chandrakar, Purvi
    Ahmad, Ashfaque
    Powiązania:
    https://bibliotekanauki.pl/articles/240435.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    artificial neural network
    solar air heater
    thermal performance
    multilayer perceptron
    Opis:
    Solar air heater (SAH) is an important device for solar energy utilization which is used for space heating, crop drying, timber seasoning etc. Its performance mainly depends on system parameters, operating parameters and meteorological parameters. Many researchers have been used these parameters to predict the performance of SAH by analytical or conventional approach and artificial neural network (ANN) technique, but performance prediction of SAH by using relevant input parameters has not been done so far. Therefore, relevant input parameters have been considered in this study. Total ten parameters were used such as mass flow rate, ambient temperature, wind speed, relative humidity, fluid inlet temperature, fluid mean temperature, plate temperature, wind direction, solar elevation and solar intensity to find out the relevant parameters for ANN prediction. Seven different neural models have been constructed using these parameters. In each model 10 to 20 neurons have been selected to find out the optimal model. The optimal neural models for ANN-I, ANN-II, ANN-III, ANN-IV, ANN-V, ANN-VI and ANN-VII were obtained as 10-17-1, 8-14-1, 6-16-1, 5- 14-1, 4-17-1, 3-16-1 and 2-14-1, respectively. It has been found that ANN-II model with 8-14-1 is the optimal model as compared to other neural models. Values of the sum of squared errors, mean relative error, and coefficient of determination were found to be 0.02138, 1.82% and 0.99387, respectively, which shows that the ANN-II developed with mass flow rate, ambient temperature, inlet and mean temperature of air, plate temperature, wind speed and direction, relative humidity, and relevant input parameters performed better. The above results show that these eight parameters are relevant for prediction.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 3; 255-282
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A comprehensive review on energy and exergy analysis of solar air heaters
    Autorzy:
    Ghritlahre, Harish Kumar
    Sahu, Piyush Kumar
    Powiązania:
    https://bibliotekanauki.pl/articles/240351.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    solar energy
    energy
    exergy analysis
    solar air heater
    thermal performance
    Opis:
    For economic growth of nation, the energy plays an important role. The excessive use of fossil fuels results the increase in global warming and depleting the resources. Due to this reason, the renewable energy sources are creating more attraction for researchers. In renewable energy sector, solar energy is the most abundant and clean source of energy. In solar thermal systems, solar air heater (SAH) is the main system which is used for heating of air. As it is simple in construction and cheaper in cost, it is of main interest for the researchers. The concept of first law and second law of thermodynamics is used for the study of the energy and exergy analysis respectively. The energy analysis is of great importance for the study of process effectiveness while the exergetic analysis is another significant concept to examine the actual behavior of process involving various energy losses and internal irreversibility. For efficient utilization of solar energy, the exergy analysis is very important tool for optimal design of solar air heaters. The aim of the present work is to review the works related to energy and exergy analysis of various types of solar air heaters and to find out the research gap for future work.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 3; 183-222
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of serrated circular rings on heat transfer augmentation of circular tube heat exchanger
    Autorzy:
    Kharkwal, Himanshi
    Singh, Satyendra
    Powiązania:
    https://bibliotekanauki.pl/articles/2091375.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    heat transfer rate
    friction factor
    thermal performance factor
    serrated circular ring
    Opis:
    Limiting energy resources has led researchers to find new innovative ways to enhance heat exchanging devices thermal performance in power generating systems. Thus, the present paper analyzes passive techniques of enhancing the thermal performance of a single tube heat exchanger. Experimental and numerical investigation on heat transfer enhancement using aserrated circular ring with twisted tape is carried out. The work incorporates the determination of Nusselt number, friction factor, thermal performance factor for serrated circular ring with twisted tape with variation in diameter ratio (0.8 and 0.85) and pitch ratio (2 and 3). Air is used as a working fluid with Reynolds number 6000–24000. The experiment is conducted by providing a constant wall heat flux of 1000 W/m2 to the system and thereby taking results at a steady state. The experimental and computational findings obtained for the smooth tube case are compared with the standard correlations of Dittus–Boelter and Blasius. Based on experimental and numerical investigation, there is 5.16 times augmentation in heat transfer and 3.05 times improvement in thermal performance factor over the smooth tube heat exchanger. In addition, the study of entropy generation rate for every geometrical parameter has been conducted, and their influence on the system’s thermal behaviour is presented. The results obtained in the present study may help the researchers of the same research area to find similar inserts and new ways of enhancing the thermal performance of heat exchangers.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 2; 129--155
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental investigation of augmented thermal and performance characteristics of solar air heater ducts due to varied orientations of roughness geometry on the absorber plate
    Autorzy:
    Sahu, Mukesh Kumar
    Matheswaran, M. M.
    Bishnoi, Pardeep
    Powiązania:
    https://bibliotekanauki.pl/articles/239981.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    solar air heater
    SAH
    thermal efficiency
    heat removal factor
    collector efficiency factor
    artificial roughness
    heat transfer rate
    Opis:
    This paper presents the outdoor experimental results for thermal performance analysis of artificially roughened solar air heaters (SAHs). Circular wire ribs have been arranged to form arc shape geometry on the absorber plates and have been tested for two configurations of SAHs named as arc shape apex-downstream flow and arc shape apex-upstream flow SAH. Roughness parameters have been taken as relative roughness pitch in the range of 8–15, angle of attack 45°–75°, and for fixed relative roughness height of 0.0454, duct width to duct height ratio of 11. During the experimental analysis the mass flow rate varied from 0.0100 to 0.0471 kg/s. Based on the experimental results it was found that roughness with apexupstream flow SAH is having higher value of thermal efficiency, heat removal factor and collector efficiency factor as compared to roughness with apexdownstream flow SAH and simple absorber plate SAH. In the range of the operating parameters investigated the maximum of thermal efficiency, heat removal factor, and collector efficiency factor have been found.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 3; 147-182
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance analysis of three sides solar air heater having roughness elements as a combination of multiple-v and transverse wire on the absorber plate
    Autorzy:
    Kumar, Dhananjay
    Prasad, Laljee
    Powiązania:
    https://bibliotekanauki.pl/articles/240604.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Reynolds number
    relative roughness height
    relative roughness pitch
    solar air heater
    thermal efficiency
    one side roughened duct
    three side’s roughened duct
    Opis:
    Artificial roughness has been found to enhance the thermal performance from the collector to air in the solar air heater duct. This paper presents the results of experimental investigation on thermal performance of three sides solar air heater roughened with combination of multiple-v and transverse wire. The range of variation of system and operating parameters is investigated within the limits of relative roughness pitch of 10−25, relative roughness height of 0.018 −0.042, angle of attack of 30°−75° at varying flow Reynolds number in the of range of 3000−12000 for fixed value of relative roughness width of 6. The augmentation in fluid temperature flowing under three side’s roughened duct is found to be 36.57% more than that of one side roughened duct. The maximum thermal efficiency is obtained at relative roughness pitch of 10 and relative roughness height of 0.042, and angle of attack of 60°. The augmentation in thermal efficiency of three sides over those of one side roughened duct is found to be 46−57% for varying values of relative roughness pitch, 38−50% for varying values of relative roughness height, and 40−46% for varying values of angle of attack.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 3; 125-146
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimisation of the performance of a pyrolysis reactor for G50 chips
    Autorzy:
    Dhaundiyal, Alok
    Singh, Suraj
    Powiązania:
    https://bibliotekanauki.pl/articles/240925.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    biomass
    thermal analysis
    pyrolysis
    gas yield
    performance index
    Opis:
    The aim of any industrial plant, which is dealing in the energy sector, is to maximise the revenue generation at the lowest production cost. It can be carried out either by optimizing the manpower or by improving the performance index of the overall unit. This paper focuses on the optimisation of a biomass power plant which is powered by G50 hardwood chips (Austrian standard for biomass chips). The experiments are conducted at different operating conditions. The overall effect of the enhanced abilities of a reactor on the power generation is examined. The output enthalpy of a generated gas, the gas yield of a reactor and the driving mechanism of the pyrolysis are examined in this analysis. The thermal efficiency of the plant is found to vary from 44 to 47% at 400°C, whereas it is 44 to 48% for running the same unit at 600°C. The transient thermal condition is solved with the help of the lumped capacitance method. The thermal efficiency of the same design, within the constraint limit, is enhanced by 5.5%, whereas the enthalpy of the produced gas is magnified by 49.49% through nonlinear optimisation. The temperature of biomass should be homogenous, and the ramping rate must be very high. The 16% rise in temperature of the reactor is required to reduce the mass yield by 20.17%. The gas yield of the reactor is increased by up to 85%. The thermal assessment indicates that the bed is thermally thin, thus the exterior heat transfer rate is a deciding factor of the pyrolysis in the reactor.
    Źródło:
    Archives of Thermodynamics; 2020, 41, 1; 245-263
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Assessing the performance of the airflow window for ventilation and thermal comfort in office rooms
    Autorzy:
    Fathi Ajirlou, Ildar
    Kurtay, Cüneyt
    Powiązania:
    https://bibliotekanauki.pl/articles/1955029.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    HVAC
    natural ventilation
    air-flow window
    thermal comfort
    contaminant removal
    Opis:
    In the present study performance of an airflow window in removing contaminants as well as providing thermal comfort for the occupants was investigated. Both natural/mixed ventilation methods were studied and the full heating load as well as contaminant sources in the office rooms considered. Then, the local and average temperature, relative humidity, velocity as well as CO2 and dust concentration were extracted from simulation results and compared to criteria in international ventilation standards. It was found that except in the big room having 8 m×6 m flooring, natural ventilation from the airflow window can satisfy the thermal and relative humidity conditions in the international ventilation standard except for the American Society of Heating, Refrigerating and Air-Conditioning Engineers. However, the thermal comfort in the room which was measured by extended predicted mean vote could not be achieved when the window operates in the natural ventilation mode, even with a 0.4 m height opening in the small (3 m×4 m) room. Finally, results indicated that the airflow ventilation system installed in small and medium offices operation can provide indoor condition in the ventilation standard either in natural/mixed operation mode consuming less energy than the traditional heating, ventilation, and air conditioning. Besides, the airflow system not only was not able to provide thermal comfort condition in the big office but also its application was not economically feasible.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 3; 209-242
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance analysis and PCM selection for adsorption chiller aided by energy storage supplied from the district heating system
    Autorzy:
    Karwacki, Jarosław
    Kwidziński, Roman
    Leputa, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/2204066.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal sorption cooling
    phase change material
    thermal energy storage
    district heating
    adsorption
    energy management
    mathematical modelling
    load shifting
    efficiency
    Opis:
    The paper presents a theoretical analysis of thermal energy storage filled with phase change material (PCM) that is aimed at optimization of an adsorption chiller performance in an air-conditioning system. The equations describing a lumped parameter model were used to analyze internal heat transfer in the cooling installation. Those equations result from the energy balances of the chiller, PCM thermal storage unit and heat load. The influence of the control of the heat transfer fluid flow rate and heat capacity of the system components on the whole system operation was investigated. The model was used to validate the selection of Rubitherm RT62HC as a PCM for thermal storage. It also allowed us to assess the temperature levels that are likely to appear during the operation of the system before it will be constructed.
    Źródło:
    Archives of Thermodynamics; 2022, 43, 4; 135--169
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Exergetic performance analysis of solar air heater with inverted L-shape ribs as roughness element
    Autorzy:
    Chaudhari, Manmohan
    Sharma, Sohan Lal
    Debbarma, Ajoy
    Powiązania:
    https://bibliotekanauki.pl/articles/27312231.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    solar air heater
    heat transfer
    exergy loss
    exergy efficiency
    thermal efficiency
    Opis:
    Improvement in the exegetic efficiency of a solar air heater (SAH) can be done by enhancing the rate of heat transfer. In this work, the exergetic efficiency optimization of an artificially roughened solar air heater having an inverted L-shape rib has been performed. The numerical analysis of the exergetic performance of the solar air heater was carried out at a constant heat flux of 1000 W/m2 . The study was conducted to investigate the effect of different relative roughness pitch (7.14–17.86) on the exergy losses, under the Reynolds number range of 3000 to 18 000. The roughness parameter of this geometry has been optimized and found to be among functional operating parameters like average solar intensity and temperature rise across the collector. The optimized value of relative roughness pitch is 17.86 at the isolation of 1000 W/m2 , and the parameter of temperature rise ranges from 0.005 to 0.04.
    Źródło:
    Archives of Thermodynamics; 2023, 44, 3; 241--267
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mathematical modeling of hydrogen production performance in thermocatalytic reactor based on the intermetallic phase of Ni3Al
    Autorzy:
    Badur, Janusz
    Stajnke, Michał
    Ziółkowski, Paweł
    Jóźwik, Paweł
    Bojar, Zbigniew
    Ziółkowski, Piotr Józef
    Powiązania:
    https://bibliotekanauki.pl/articles/240134.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal decomposition
    species transport
    catalyst
    CFD
    rozkład termiczny
    katalizator
    Opis:
    The main goal of the considered work is to adjust mathematical modeling for mass transfer, to specific conditions resulting from presence of chemical surface reactions in the flow of the mixture consisting of helium and methanol. The thermocatalytic devices used for decomposition of organic compounds incorporate microchannels coupled at the ends and heated to 500ºC at the walls regions. The experiment data were compared with computational fluid dynamics results to calibrate the constants of the model’s user defined functions. These extensions allow to transform the calculations mechanisms and algorithms of commercial codes adapting them for the microflows cases and increased chemical reactions rate on the interphase between fluid and solid, specific for catalytic reactions. Results obtained on the way of numerical calculations have been calibrated and compared with the experimental data to receive satisfactory compliance. The model has been verified and the performance of the thermocatalytic reactor with microchannels under hydrogen production regime has been investigated.
    Źródło:
    Archives of Thermodynamics; 2019, 40, 3; 3-26
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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