The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
J.s. Neymark - One of the best experts on this subject based on the ideXlab platform.
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Adaptation of the BESTEST intermodel comparison method for proposed ASHRAE Standard 140P: Method of test for building energy simulation programs
1999Co-Authors: R.d. Judkoff, J.s. NeymarkAbstract:An ASHRAE Standard Method of Test is being developed for systematically testing whole-building energy simulation models and diagnosing the sources of predictive disagreement. The procedure, ASHRAE Proposed Standard 140P, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs, uses the comparative testing approach. In this method, a set of test cases is carefully defined so that equivalent input files can be developed for a variety of detailed and simplified whole building energy simulation programs. Results are then generated and compared using a variety of detailed simulation programs and/or different versions of one simulation program. In the proposed ASHRAE Standard 140P, the tests progress systematically from extremely simple to relatively realistic. The more realistic cases, while geometrically simple, test the ability of the programs to model such combined effects as thermal mass, direct solar gain windows, window shading devices, internally generated Heat, Infiltration, sunspaces, and dead-band and set-back thermostat control. The more simplified cases facilitate diagnosis by allowing excitation of particular Heat transfer mechanisms. Output values for the cases, such as annual loads, annual maximum and minimum temperatures, peak loads, and some hourly data, are compared and used in conjunction with diagnostic logic to determine the algorithmsmore » responsible for prediction differences.« less
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A procedure for testing the ability of whole building energy simulation programs to thermally model the building fabric
Journal of Solar Energy Engineering, 1995Co-Authors: R.d. Judkoff, J.s. NeymarkAbstract:A procedure was developed for systematically testing whole building energy simulation models and diagnosing the sources of predictive disagreements. Field trials of the method were conducted with a number of detailed state-of-the-art programs by researchers from nations participating in International Energy Agency (IEA) Task 12 and Annex 21. The technique consists of a series of carefully specified test case buildings that progress systematically from extremely simple to relatively realistic. Output values for the cases, such as annual loads, annual maximum and minimum temperatures, peak loads, and some hourly data are compared, and used in conjunction with diagnostic logic to determine the algorithm responsible for prediction differences. The more realistic cases, while geometrically simple, test the ability of the programs to model such combined effects as thermal mass, direct solar gain windows, window shading devices, internally generated Heat, Infiltration, sunspaces, earth coupling, and deadband and setback thermostat control. The more simplified cases facilitate diagnosis by allowing excitation of particular Heat transfer mechanisms. The procedure was very effective at revealing bugs, faulty algorithms, and input errors in a group of building energy simulation programs that may be considered among the world`s best. The output data from the simulation programs can be usedmore » as reference ranges for comparing and diagnosing other detailed or simplified design tools.« less
Zhongie Huan - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Overall Heat Transfer Coefficient of Composite Panels for Thermal Insulation
Applied Mechanics and Materials, 2017Co-Authors: Tamba Jamiru, Oludaisi Adekomaya, Rotimi Sadiku, Zhongie HuanAbstract:Heat Infiltration through the external wall of refrigerated vehicles has been a concern to food industries considering high thermal load required to sustain unbroken cold chain. In this research, experiments were carried out with known fibres contents laid out at various orientations and the effect on the Heat transfer measured. The results indicate that the estimated overall Heat transfer coefficient of the composite reinforced with 10%wt. of fibre at 0o orientation (G10E) offers the lowest U value of 0.386950 W/m2K and 0.196680 W/m2K for 50 mm and 100 mm insulation thicknesses respectively. The effect of fiber orientation in the composite panel in energy saving was to a large extent minimal when compared to the un-oriented composite panel
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Minimizing energy consumption in refrigerated vehicles through alternative external wall
Renewable and Sustainable Energy Reviews, 2017Co-Authors: Oludaisi Adekomaya, Tamba Jamiru, Rotimi Sadiku, Zhongie HuanAbstract:Transporting fresh foods and raw agricultural produce have been widely acknowledged as a critical aspect of food chain. Raw fresh food must be conveyed at a low temperature conditions to preserve quality and prolong the shelf life of transported food. This paper takes an insight look at food transport system and proffers a sustainable ways of reducing energy consumption in diesel engine driven vapour compression system. Many studies have reported that 15% of world total energy is used in food preservation while some authors have predicted additional 2% annual increment of energy demand to sustain food chain. In the course of this study, the authors pragmatically identified sources of energy demand in food transport and maintained that the best approach to minimise energy consumption in refrigerated vehicles is to find a light weight and low thermal conductivity material as the external wall of refrigerated vehicles. This research is of high interest in view of continuous rise in earth temperature occasioned by emission of carbon monoxide from fossil fuel. The authors further showed that the usage of aluminium sheet as external wall of refrigerated vehicles reduces the longevity of insulation which increases Heat Infiltration into the cooling chamber thereby aggravating energy demand.
Mônica Elisabeth Torres Prado - One of the best experts on this subject based on the ideXlab platform.
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Heat transfer and energy consumption in the freezing of guava pulp in large containers
Applied Thermal Engineering, 2011Co-Authors: M. J. Reno, Jaime Vilela De Resende, A. P. Peres, T.m.o. Giarolla, Mônica Elisabeth Torres PradoAbstract:Abstract The Heat transfer process, including the convective transfer coefficients (h), freezing times and power consumption, was evaluated during the air blast freezing of 600 kg of guava pulp. Three packaging configurations were tested: plastic boxes (34 L), buckets (20 L) and metal drums (200 L). The air velocity inside the freezer tunnel was measured at several points, and sensors were installed to monitor the temperature. The Heat Infiltration from external ambient air was also verified. Correlations of the Nusselt number versus the Reynolds and Prandtl numbers were used to estimate the convective Heat transfer coefficients according to the configuration of the systems. The coefficients were applied to freezing-time prediction models. The h values and consequent freezing time prediction were found to be more precise for the packaging in the bucket configuration. For the drum configuration, the correlation that considered the turbulence factor effects was found to be satisfactory. In the box configuration, the correlation produced good results only for the boxes located in the central area of the stack. The results indicate that the correlations may be applicable to the analysis and the differences explained by airflow and the difficulty of maintaining constant Heat flow on the surfaces.
Biju T. Kuzhiveli - One of the best experts on this subject based on the ideXlab platform.
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Evolution of stratification in a cryogenic propellant tank at reduced gravity environment
IOP Conference Series: Materials Science and Engineering, 2019Co-Authors: S. B. Vishnu, Biju T. KuzhiveliAbstract:The prediction of thermal stratification in a cryogenic storage tank is necessary for the successful execution of space mission. The working fluid may be stored in the sub-cooled conditions and possibility of Heat Infiltration may lead to the increase of temperature as well as the pressure of the cryogenic fluid. The rise in fluid pressure may also lead to cavitation in the turbo pump which has to be avoided. Commonly used stratification models are based on temperature and velocity correlation developed for flow over a flat plate. An experimental cryogenic test tank is designed, fabricated and stratification is studied using nitrogen as the model propellant. The effect of gravity on the evolution of stratification is studied by using a CFD model. The results show that the fluid velocity will be lesser at microgravity condition which causes the boundary layer fluid to absorb a large amount of Heat and the nature of the Heat transfer changes from convection to evaporation.
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Effect of micro- and elevated gravity condition on the evolution of stratification and self-pressurization in a cryogenic propellant tank
Sādhanā, 2019Co-Authors: S. B. Vishnu, Biju T. KuzhiveliAbstract:An efficient way of handling and storing cryogenic propellant is required for future space exploration. In rocketry applications, propellants are stored at subcooled conditions in foam-insulated tanks. Any kind of Heat Infiltration may lead to stratification and self-pressurization of the tank. The supply of warm propellant beyond the cavitation limit to a turbo-pump is dangerous and hence additional propellant has to be loaded, which affects the payload capacity. The evolution of stratification during lift-off and accelerated conditions and coast phase will be different from those during normal ambient conditions. During lift-off the gravity value can reach up to 6 g and microgravity (μg) conditions at the coast phase. Hence, accurate prediction of the state of propellant at all stage is required for the successful mission planning. A multiphase axis-symmetric CFD model is developed, which can simultaneously account for Heat transfer from the ambient and Heat exchanges within the fluids during different gravity conditions. The results show that the self-pressurisation in microgravity condition is due to phase change rather than thermal stratification. The flow velocity will be maximum during lift-off and accelerated condition. Hence, greater self-pressurisation happens during the initial period and reduction in pressure rise rate is noticed later, which is due to turbulence of the fluid.
R.d. Judkoff - One of the best experts on this subject based on the ideXlab platform.
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Adaptation of the BESTEST intermodel comparison method for proposed ASHRAE Standard 140P: Method of test for building energy simulation programs
1999Co-Authors: R.d. Judkoff, J.s. NeymarkAbstract:An ASHRAE Standard Method of Test is being developed for systematically testing whole-building energy simulation models and diagnosing the sources of predictive disagreement. The procedure, ASHRAE Proposed Standard 140P, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs, uses the comparative testing approach. In this method, a set of test cases is carefully defined so that equivalent input files can be developed for a variety of detailed and simplified whole building energy simulation programs. Results are then generated and compared using a variety of detailed simulation programs and/or different versions of one simulation program. In the proposed ASHRAE Standard 140P, the tests progress systematically from extremely simple to relatively realistic. The more realistic cases, while geometrically simple, test the ability of the programs to model such combined effects as thermal mass, direct solar gain windows, window shading devices, internally generated Heat, Infiltration, sunspaces, and dead-band and set-back thermostat control. The more simplified cases facilitate diagnosis by allowing excitation of particular Heat transfer mechanisms. Output values for the cases, such as annual loads, annual maximum and minimum temperatures, peak loads, and some hourly data, are compared and used in conjunction with diagnostic logic to determine the algorithmsmore » responsible for prediction differences.« less
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A procedure for testing the ability of whole building energy simulation programs to thermally model the building fabric
Journal of Solar Energy Engineering, 1995Co-Authors: R.d. Judkoff, J.s. NeymarkAbstract:A procedure was developed for systematically testing whole building energy simulation models and diagnosing the sources of predictive disagreements. Field trials of the method were conducted with a number of detailed state-of-the-art programs by researchers from nations participating in International Energy Agency (IEA) Task 12 and Annex 21. The technique consists of a series of carefully specified test case buildings that progress systematically from extremely simple to relatively realistic. Output values for the cases, such as annual loads, annual maximum and minimum temperatures, peak loads, and some hourly data are compared, and used in conjunction with diagnostic logic to determine the algorithm responsible for prediction differences. The more realistic cases, while geometrically simple, test the ability of the programs to model such combined effects as thermal mass, direct solar gain windows, window shading devices, internally generated Heat, Infiltration, sunspaces, earth coupling, and deadband and setback thermostat control. The more simplified cases facilitate diagnosis by allowing excitation of particular Heat transfer mechanisms. The procedure was very effective at revealing bugs, faulty algorithms, and input errors in a group of building energy simulation programs that may be considered among the world`s best. The output data from the simulation programs can be usedmore » as reference ranges for comparing and diagnosing other detailed or simplified design tools.« less
