The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Yasuyuki Ikegami - One of the best experts on this subject based on the ideXlab platform.

  • optimum design criteria for an organic rankine cycle using low temperature geothermal Heat Sources
    Energy, 2007
    Co-Authors: H Madhawa D Hettiarachchi, Mihajlo Golubovic, W M Worek, Yasuyuki Ikegami
    Abstract:

    A cost-effective optimum design criterion for Organic Rankine power cycles utilizing low-temperature geothermal Heat Sources is presented. The ratio of the total Heat exchanger area to net power output is used as the objective function and was optimized using the steepest descent method. Evaporation and condensation temperatures, geothermal and cooling water velocities are varied in the optimization method. The optimum cycle performance is evaluated and compared for working fluids that include ammonia, HCFC123, n-Pentane and PF5050. The optimization method converges to a unique solution for specific values of evaporation and condensation temperatures and geothermal and cooling water velocities. The choice of working fluid can be greatly affect the objective function which is a measure of power plant cost and in some instances the difference could be more than twice. Ammonia has minimum objective function and maximum geothermal water utilization, but not necessarily maximum cycle efficiency. Exergy analysis shows that efficiency of the ammonia cycle has been largely compromised in the optimization process than that of other working fluids. The fluids, HCFC 123 and n-Pentane, have better performance than PF 5050, although the latter has most preferable physical and chemical characteristics compared to other fluids considered.

  • The Performance of the Kalina Cycle System 11(KCS-11) With Low-Temperature Heat Sources
    Journal of Energy Resources Technology-transactions of The Asme, 2007
    Co-Authors: H.d. Madhawa Hettiarachchi, Mihajlo Golubovic, William M. Worek, Yasuyuki Ikegami
    Abstract:

    The possibility of exploiting low-temperature Heat Sources has been of great significance with ever increasing energy demand. Optimum and cost-effective design of the power cycles provide a means of utilization of low-temperature Heat Sources which might otherwise be discarded. In this analysis, the performance of the Kalina cycle system 11 (KCS11) is examined for low-temperature geothermal Heat Sources and is compared with an organic Rankine cycle. The effect of the ammonia fraction and turbine inlet pressure on the cycle performance is investigated in detail. Results show that for a given turbine inlet pressure, an optimum ammonia fraction can be found that yields the maximum cycle efficiency. Further, the maximum cycle efficiency does not necessarily yield the optimum operating conditions for the system. In addition, it is important to consider the utilization of the various circulating media (i.e., working fluid, cooling water, and Heat resource) and Heat exchanger area per unit power produced. For given conditions, an optimum range of operating pressure and ammonia fraction can be identified that result in optimum cycle performance. In general, the KCS11 has better overall performance at moderate pressures than that of the organic Rankine cycle.

William Dhaeseleer - One of the best experts on this subject based on the ideXlab platform.

  • comparison of thermodynamic cycles for power production from low temperature geothermal Heat Sources
    Energy Conversion and Management, 2013
    Co-Authors: Daniel Walraven, Ben Laenen, William Dhaeseleer
    Abstract:

    Abstract The performance of different types of organic Rankine cycles (ORCs) and of the Kalina cycle is investigated and optimized for low-temperature (100–150 °C) geothermal Heat Sources. A variety of configurations is worth considering. The ORCs can be subcritical or transcritical and can have one or more pressure levels. Each cycle can be a simple one, have recuperation or turbine bleeding and up to 80 different working fluids can be used. Comparison of these cycles to each other and to an optimized Kalina cycle concludes that the transcritical and multi-pressure subcritical cycles are the best ones. Exergetic plant efficiencies of above 50% can be achieved when the brine is allowed to cool down as much as possible. A constraint on the brine outlet temperature causes a strong decrease in the mechanical power output of the cycle. Due to the low Heat source temperatures, a low condenser temperature and small temperature differences in the Heat exchanger are very important.

Sylvai Quoili - One of the best experts on this subject based on the ideXlab platform.

  • categorization and analysis of Heat Sources for organic rankine cycle systems
    Renewable & Sustainable Energy Reviews, 2016
    Co-Authors: Huixing Zhai, Qingsong A, Li Shi, Vince Lemo, Sylvai Quoili
    Abstract:

    Organic Rankine cycles (ORC) are an effective way to convert low-medium temperature Heat to electricity that cannot be used for conventional high-temperature Rankine cycles. Even though there has been many studies of ORC systems over the past few decades, ORC Heat Sources have received relatively little attention. The Heat Sources providing energy to the ORC have different characteristics that significantly impact the theoretical analyses and system designs of ORC systems. This paper gives a theoretical categorization of Heat Sources to give uniform boundary conditions for further theoretical studies on cycle choices and working fluid screening. The ideal cycles for each Heat source type are analyzed. Performance metrics are recommended for different Heat source ORC systems. The general characteristics of the different Heat Sources including waste Heat from industrial and power systems and geothermal, solar and biomass Sources are given with their influences on the ORC systems. Finally, the market characteristics for ORC systems using different Heat Sources are reviewed with suggestions for future developments of ORC systems.

Faruk Kaynakli - One of the best experts on this subject based on the ideXlab platform.

  • energy and exergy analysis of a double effect absorption refrigeration system based on different Heat Sources
    Energy Conversion and Management, 2015
    Co-Authors: Omer Kaynakli, Kenan Saka, Faruk Kaynakli
    Abstract:

    Abstract Absorption refrigeration systems are environmental friendly since they can utilize industrial waste Heat and/or solar energy. In terms of Heat source of the systems, researchers prefer one type Heat source usually such as hot water or steam. Some studies can be free from environment. In this study, energy and exergy analysis is performed on a double effect series flow absorption refrigeration system with water/lithium bromide as working fluid pair. The refrigeration system runs on various Heat Sources such as hot water, hot air and steam via High Pressure Generator (HPG) because of hot water/steam and hot air are the most common available Heat source for absorption applications but the first law of thermodynamics may not be sufficient analyze the absorption refrigeration system and to show the difference of utilize for different type Heat source. On the other hand operation temperatures of the overall system and its components have a major effect on their performance and functionality. In this regard, a parametric study conducted here to investigate this effect on Heat capacity and exergy destruction of the HPG, coefficient of performance (COP) of the system, and mass flow rate of Heat Sources. Also, a comparative analysis is carried out on several Heat Sources (e.g. hot water, hot air and steam) in terms of exergy destruction and mass flow rate of Heat source. From the analyses it is observed that exergy destruction of the HPG increases at higher temperature of the Heat Sources, condenser and absorber, and lower temperature of the HPG, LPG and evaporator. This destruction is maximized when hot air Heat source is used and minimized with utilizing hot water Heat source.

Hongguang Jin - One of the best experts on this subject based on the ideXlab platform.

  • analysis of an absorption absorption compression refrigeration system for Heat Sources with large temperature change
    Energy Conversion and Management, 2016
    Co-Authors: Yi Chen, Wei Han, Hongguang Jin
    Abstract:

    Abstract Absorption refrigeration systems are a promising way to reduce electricity consumption in the field of refrigeration and cooling. To improve the thermal energy utilization performance of the absorption refrigeration system, an absorption/absorption–compression refrigeration system with a large working range is proposed in this paper. The new system consists of a conventional single-effect absorption subcycle and an absorption–compression refrigeration subcycle, and they share the condenser, evaporator, absorber and some other relative components. The temperature of the waste gas exhausted from the system can be 35 °C lower than that of the waste gas from a traditional, single-effect absorption refrigeration system. For the proposed system, the cooling capacity per unit mass of flue gas reaches 58.95 kJ kg −1 when the evaporation temperature is −15 °C, which is 28.21% higher than that of the single-effect absorption refrigeration system. The exergy efficiency of the proposed system is as high as 25.94%. To indicate the direction of system optimization, the new system is further studied using a parametric analysis. The new absorption/absorption–compression refrigeration system provides a promising way to efficiently utilize Heat Sources with large temperature change or multiple Heat Sources with different temperatures.