The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Abraham Kribus - One of the best experts on this subject based on the ideXlab platform.

  • Performance of the Solar hybrid STIG cycle with latent heat storage
    Applied Energy, 2015
    Co-Authors: Guy Polonsky, Abraham Kribus
    Abstract:

    Abstract The Solar hybrid Steam Injection Gas turbine (STIG) cycle uses both recuperated heat and Solar heat in order to generate steam at a low temperature and pressure, and inject it into the cycle in order to augment the power output. This work addresses the addition of thermal energy storage to allow operation from Solar energy beyond the daylight hours. An Annual performance analysis of the Solar STIG cycle with latent heat phase change material (PCM) storage is presented for the climatic conditions of Sede Boqer, Israel. We show that the heat transfer limitation present in a real PCM storage leads to a slight performance penalty only compared to an ideal storage. We also analyze the impact of shifting electricity generation from daytime to evening, which can lead to a surprisingly high contribution of the thermal storage. Results show Annual Solar Fraction of up to 35.2%. The Annual Solar to electricity efficiency was 20.1% when using the recuperated Brayton cycle as reference, and 13.9% for an optimal conventional STIG cycle as reference. These values are similar to or higher than the Annual efficiency of current Solar thermal power technologies, even though the hybrid STIG cycle uses low-grade Solar heat at 200–280 °C.

  • Annual performance of the Solar hybrid STIG cycle
    Solar Energy, 2014
    Co-Authors: Guy Polonsky, Maya Livshits, A. Immanuel Selwynraj, S. Iniyan, L. Suganthi, Abraham Kribus
    Abstract:

    Abstract The Solar hybrid Steam Injection Gas turbine (STIG) cycle uses both recuperated heat and Solar heat in order to generate steam at a low temperature and pressure, and inject it into the cycle in order to augment the power output. An Annual performance analysis of the Solar STIG cycle is presented for sites in Israel and India, with moderate and high Annual direct insolation. The cycle operation was simulated in two modes: constant power output and variable power output following the variation of Solar input. The Solar contribution to the electricity production of the hybrid cycle and the Solar to electricity efficiency were calculated, where the conventional reference system was either a conventional STIG or a conventional recuperated Brayton cycle. Results show Annual Solar Fraction of up to 31% in constant power mode and up to 33% in variable power mode. The Annual Solar to electricity efficiency was in the range of 22–26% when the reference efficiency was based on the recuperated Brayton cycle, and 12–16% when the reference efficiency was based on an optimal conventional STIG cycle. These values are similar to or higher than the Annual efficiency of current Solar thermal power technologies, even though the hybrid STIG cycle uses low-grade Solar heat at only 200 °C.

Guy Polonsky - One of the best experts on this subject based on the ideXlab platform.

  • Performance of the Solar hybrid STIG cycle with latent heat storage
    Applied Energy, 2015
    Co-Authors: Guy Polonsky, Abraham Kribus
    Abstract:

    Abstract The Solar hybrid Steam Injection Gas turbine (STIG) cycle uses both recuperated heat and Solar heat in order to generate steam at a low temperature and pressure, and inject it into the cycle in order to augment the power output. This work addresses the addition of thermal energy storage to allow operation from Solar energy beyond the daylight hours. An Annual performance analysis of the Solar STIG cycle with latent heat phase change material (PCM) storage is presented for the climatic conditions of Sede Boqer, Israel. We show that the heat transfer limitation present in a real PCM storage leads to a slight performance penalty only compared to an ideal storage. We also analyze the impact of shifting electricity generation from daytime to evening, which can lead to a surprisingly high contribution of the thermal storage. Results show Annual Solar Fraction of up to 35.2%. The Annual Solar to electricity efficiency was 20.1% when using the recuperated Brayton cycle as reference, and 13.9% for an optimal conventional STIG cycle as reference. These values are similar to or higher than the Annual efficiency of current Solar thermal power technologies, even though the hybrid STIG cycle uses low-grade Solar heat at 200–280 °C.

  • Annual performance of the Solar hybrid STIG cycle
    Solar Energy, 2014
    Co-Authors: Guy Polonsky, Maya Livshits, A. Immanuel Selwynraj, S. Iniyan, L. Suganthi, Abraham Kribus
    Abstract:

    Abstract The Solar hybrid Steam Injection Gas turbine (STIG) cycle uses both recuperated heat and Solar heat in order to generate steam at a low temperature and pressure, and inject it into the cycle in order to augment the power output. An Annual performance analysis of the Solar STIG cycle is presented for sites in Israel and India, with moderate and high Annual direct insolation. The cycle operation was simulated in two modes: constant power output and variable power output following the variation of Solar input. The Solar contribution to the electricity production of the hybrid cycle and the Solar to electricity efficiency were calculated, where the conventional reference system was either a conventional STIG or a conventional recuperated Brayton cycle. Results show Annual Solar Fraction of up to 31% in constant power mode and up to 33% in variable power mode. The Annual Solar to electricity efficiency was in the range of 22–26% when the reference efficiency was based on the recuperated Brayton cycle, and 12–16% when the reference efficiency was based on an optimal conventional STIG cycle. These values are similar to or higher than the Annual efficiency of current Solar thermal power technologies, even though the hybrid STIG cycle uses low-grade Solar heat at only 200 °C.

Adnan Shariah - One of the best experts on this subject based on the ideXlab platform.

  • Optimizing the tilt angle of Solar collectors
    Renewable Energy, 2002
    Co-Authors: Adnan Shariah, M-ali Al-akhras, Islam Al Omari
    Abstract:

    Solar collectors need to be tilted at the correct angle to maximize the performance of the system. In this paper, the Annual Solar Fraction of the system (the Fraction of energy that is supplied by Solar energy) is used as an indicator to find the optimum inclination angles for a thermosyphon Solar water heater installed in northern and southern parts of Jordan. Calculations are carried out using the powerful computer program TRNSYS (Transient System Simulation). The system is assumed to operate with a daily hot water load of 150 l at 55°C flowing during the day according to the widely used Rand consumption profile. The results show that the optimum inclination angle for the maximum Solar Fraction is about φ+(0→10°) for the northern region (represented by Amman) and about φ+(0→20°) for the southern region (represented by the town of Aqaba). These values are greater than those for maximum Solar radiation (which is commonly used as an indicator) at the top of the collector by about 5 to 8°.

  • Effect of thermal conductivity of absorber plate on the performance of a Solar water heater
    Applied Thermal Engineering, 1999
    Co-Authors: Adnan Shariah, Akram Rousan, Kh.k. Rousan, A. A. Ahmad
    Abstract:

    Abstract The effect of thermal conductivity of the absorber plate of a Solar collector on the performance of a thermosyphon Solar water heater is studied by the use of the transient simulation system (TRNSYS) computer program. The system is assumed to supply hot water at 55° and 80°C representing both domestic and industrial uses respectively. Hot water of volumes 50, 125, and 250 l is consumed daily according to the Rand distribution profile. The results have shows that the Annual Solar Fraction of the system and the collector`s characteristic factors (namely, fin efficiency factor, collector efficiency factor, and heat removal factor) have a very strong dependence on the thermal conductivity for its low values, and weak dependence is observed beyond a thermal conductivity value of 50 W/m °C for the Solar Fraction and beyond a value of 100 W/m °C for the characteristic factors. It is also observed that the Annual Solar Fraction is improved by about 4%–7% and the characteristic factors are improved by about 12%–19% when a steel absorber plate is replaced by an aluminium one, whereas, the Solar Fraction and the characteristic factors are increased only about 1% and 3%, respectively, when a copper plate is used instead of an aluminium one.

  • Optimal design for a thermosyphon Solar water heater
    Renewable Energy, 1997
    Co-Authors: Adnan Shariah, Bassam Shalabi
    Abstract:

    Through the use of TRNSYS, a transient simulation program, optimization of design parameters for a thermosyphon Solar water heater was studied for two regions in Jordan represented by two cities, namely Amman and Aqaba. The optimum value of a parameter is defined as the value which maximizes the Annual Solar Fraction of a system. This paper includes a good deal of information concerning sizing of common components of thermosyphon Solar water heaters operated under certain condition (load volume, distribution profile and temperature) using weather data of Jordan. The results indicate that the Solar Fraction of the system can be improved by 10–25% when a proper choice is used for each studied parameter. It is also shown that the Solar Fraction of a system installed in Aqaba (hot climate) is less sensitive to some parameters than the Solar Fraction of a similar installed in Amman (mild climate).

  • The optimization of tank-volume-to-collector-area ratio for a thermosyphon Solar water heater
    Renewable Energy, 1996
    Co-Authors: Adnan Shariah
    Abstract:

    Through the use of the TRNSYS simulation program, the performance of a domestic Solar water heating system operating with natural circulation (thermosyphon) and a daily hot water load has been analysed. The effect of tank height on the Annual Solar Fraction of the system has been investigated for different hot water load temperatures and storage tank volumes. Optimum values (values which maximize the Annual Solar Fraction of the system) for storage tank height and volume are calculated for operating temperatures ranging from 50 to 80°C. The response of the system to the ratio of the storage tank volume to the collector area is investigated. The dependence of the Solar Fraction on tank height was observed to be more notable in the case of large tank volumes and high load temperatures. The results indicate the existence of an optimum value for the tank volume at a given tank height and a high load temperature. At lower temperatures, the Solar Fraction rises rapidly with tank volume to a nearly constant level. An optimum value of the storage-tank-volume-to-collector-area ratio was also observed at high load temperatures.

I.m. Michaelides - One of the best experts on this subject based on the ideXlab platform.

  • simulation studies of the position of the auxiliary heater in thermosyphon Solar water heating systems
    Renewable Energy, 1997
    Co-Authors: I.m. Michaelides, D R Wilson
    Abstract:

    This paper investigates the effect of the physical location of the auxiliary source of energy in thermosyphon Solar water heaters and shows that the performance of the system can be optimised with respect to the geometry of the system components. The investigation has been based on a domestic thermosyphon Solar water heating system, which was simulated using the TRNSYS programme. The Annual Solar Fraction of the system, at the weather and socioeconomic conditions of Cyprus, is, at best, approximately 77% with an in-tank auxiliary heater configuration and 86% with an external auxiliary heater. It is demonstrated that the arrangement with the external auxiliary unit has a higher collector efficiency and results in a higher Annual Solar Fraction. In the case of in-tank auxiliary, the system performance increases with the height of the auxiliary position from the bottom of the storage tank; with the auxiliary at the bottom of the storage tank the Annual Solar Fraction is approximately 59%, compared to 77% when the auxiliary is located at the top of the tank. The system performance also depends on the height of the collector return from the bottom of the tank.

  • An investigation into the performance and cost effectiveness of thermosyphon Solar water heaters
    Renewable Energy, 1992
    Co-Authors: I.m. Michaelides, D R Wilson, W.c. Lee, P.p. Votsis
    Abstract:

    Abstract In this paper, the TRNSYS Simulation Program is used to investigate the monthly and Annual Solar Fraction of a Thermosyphon Solar Water Heater and to evaluate its economic viability in terms of its life cycle savings over a conventional water heating system. The results of the simulation indicate that the yearly Solar contribution of the system ranges from 63% for a high hot water consumption profile to 89% for a low consumption pattern. The payback period of the system is as low as 3 years when compared to electric water heating systems. As long as the competitor is diesel oil, the payback period increases to 7–9 years, depending on the hot water consumption profile used.

D R Wilson - One of the best experts on this subject based on the ideXlab platform.

  • simulation studies of the position of the auxiliary heater in thermosyphon Solar water heating systems
    Renewable Energy, 1997
    Co-Authors: I.m. Michaelides, D R Wilson
    Abstract:

    This paper investigates the effect of the physical location of the auxiliary source of energy in thermosyphon Solar water heaters and shows that the performance of the system can be optimised with respect to the geometry of the system components. The investigation has been based on a domestic thermosyphon Solar water heating system, which was simulated using the TRNSYS programme. The Annual Solar Fraction of the system, at the weather and socioeconomic conditions of Cyprus, is, at best, approximately 77% with an in-tank auxiliary heater configuration and 86% with an external auxiliary heater. It is demonstrated that the arrangement with the external auxiliary unit has a higher collector efficiency and results in a higher Annual Solar Fraction. In the case of in-tank auxiliary, the system performance increases with the height of the auxiliary position from the bottom of the storage tank; with the auxiliary at the bottom of the storage tank the Annual Solar Fraction is approximately 59%, compared to 77% when the auxiliary is located at the top of the tank. The system performance also depends on the height of the collector return from the bottom of the tank.

  • An investigation into the performance and cost effectiveness of thermosyphon Solar water heaters
    Renewable Energy, 1992
    Co-Authors: I.m. Michaelides, D R Wilson, W.c. Lee, P.p. Votsis
    Abstract:

    Abstract In this paper, the TRNSYS Simulation Program is used to investigate the monthly and Annual Solar Fraction of a Thermosyphon Solar Water Heater and to evaluate its economic viability in terms of its life cycle savings over a conventional water heating system. The results of the simulation indicate that the yearly Solar contribution of the system ranges from 63% for a high hot water consumption profile to 89% for a low consumption pattern. The payback period of the system is as low as 3 years when compared to electric water heating systems. As long as the competitor is diesel oil, the payback period increases to 7–9 years, depending on the hot water consumption profile used.