Exergy Control for a Flat-Plate Collector/Rankine Cycle Solar Power System

1991 ◽  
Vol 113 (2) ◽  
pp. 89-93 ◽  
Author(s):  
Giampaolo Manfrida ◽  
Shukuru J. M. Kawambwa
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Thermal Performance ◽  
Saturated Vapor ◽  
Rankine Cycle ◽  
Pressure Level ◽  
Heat Transfer Fluid ◽  
Second Law ◽  
Operating Pressure ◽  
Performance Study

A performance study is presented of a Rankine organic cycle powered by a low temperature solar collector. In this work a two-phase collector is considered where the heat transfer fluid is vaporized and its saturated vapor expands in a turbine according to a Rankine cycle. The collector system is divided into a boiling and a nonboiling (subcooled) part: The limit between the two depends upon the value of flow rate and radiation. A modified form of the Bliss equation is used to model the thermal performance of the collector in terms of thermal efficiency versus DTI [DTI= (Absorber average temperature-Ambient temperature)/ Solar Radiation]. The system is analyzed by second-law analysis, and it includes several exergy losses of different types (heat transfer, heat loss, etc.) which determine the overall exergy balance. Different working fluids are considered, and optimization to a certain extent is demonstrated from this point of view. In order to minimize irreversibilities and guarantee the most efficient conversion processes, the most important point is the right selection of the collector operating pressure level, which depends on the instantaneous value of radiation and ambient temperature (as well as on the collector thermal performance). The choice of the optimal pressure level is done by means of second-law arguments; the flow rates across the collector, the turbine, and the condenser are consequently determined. A simulation over a typical sunny day in Florence, Italy allows the calculation of the expected daily performance.

scholarly journals Comparison of Li2CO3-Na2CO3-K2CO3, KCl-MgCl2 and NaNO3-KNO3 as heat transfer fluid for different sCO2 and steam power cycles in CSP tower plant under different DNI conditions

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110119
Author(s):  
Kamran Mahboob ◽  
Awais A Khan ◽  
Muhammad Adeel Khan ◽  
Jawad Sarwar ◽  
Tauseef A Khan
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Rankine Cycle ◽  
Capacity Factor ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Incident Power ◽  
Steam Power ◽  
Power Cycles ◽  
Plant Configuration

This work presents the characteristics of a solar thermal tower power plant in two different places (Seville and Dubai) using three different HTFs (NaNO3-KNO3, KCl-MgCl2 and Li2CO3-Na2CO3-K2CO3) and three different power cycles (Rankine, sCO2 Recompression and sCO2 Partial cooling cycles). An indirect configuration is considered for the Gemasolar power plant. Detailed modelling is carried out for the conversion of incident power on the heliostat to the output electricity. Optimization of the cycle is carried out to determine the most promising cycle configuration for efficiency. The results showed that for the Gemasolar power plant configuration, the performance of the KCl-MgCl2 based plant was poorest amongst all. NaNO3-KNO3 based plant has shown good performance with the Rankine cycle but plant having Li2CO3-Na2CO3-K2CO3 as HTF was best for all three cycles. Partial cooling was the best performing cycle at both locations with all three HTFs. Placing the Seville Plant in Dubai has improved the efficiency from 23.56% to 24.33%, a capacity factor improvement of 21 and 52 GW additional power is generated. The optimization of the plant in Dubai has shown further improvements. The efficiency is improved, the Capacity factor is increased by 31.2 and 77.8 GW of additional electricity is produced.

scholarly journals Comparative Modeling of a Parabolic Trough Collectors Solar Power Plant with MARS Models

Energies ◽  
2017 ◽  
Vol 11 (1) ◽  
pp. 37 ◽  
Author(s):  
Jose Rogada ◽  
Lourdes Barcia ◽  
Juan Martinez ◽  
Mario Menendez ◽  
Francisco de Cos Juez
Keyword(s):  
Heat Transfer ◽  
Water Vapor ◽  
Power Plant ◽  
Solar Radiation ◽  
Thermal Energy ◽  
Power Plants ◽  
Solar Power ◽  
Rankine Cycle ◽  
Heat Transfer Fluid ◽  
Solar Field

Power plants producing energy through solar fields use a heat transfer fluid that lends itself to be influenced and changed by different variables. In solar power plants, a heat transfer fluid (HTF) is used to transfer the thermal energy of solar radiation through parabolic collectors to a water vapor Rankine cycle. In this way, a turbine is driven that produces electricity when coupled to an electric generator. These plants have a heat transfer system that converts the solar radiation into heat through a HTF, and transfers that thermal energy to the water vapor heat exchangers. The best possible performance in the Rankine cycle, and therefore in the thermal plant, is obtained when the HTF reaches its maximum temperature when leaving the solar field (SF). In addition, it is necessary that the HTF does not exceed its own maximum operating temperature, above which it degrades. The optimum temperature of the HTF is difficult to obtain, since the working conditions of the plant can change abruptly from moment to moment. Guaranteeing that this HTF operates at its optimal temperature to produce electricity through a Rankine cycle is a priority. The oil flowing through the solar field has the disadvantage of having a thermal limit. Therefore, this research focuses on trying to make sure that this fluid comes out of the solar field with the highest possible temperature. Modeling using data mining is revealed as an important tool for forecasting the performance of this kind of power plant. The purpose of this document is to provide a model that can be used to optimize the temperature control of the fluid without interfering with the normal operation of the plant. The results obtained with this model should be necessarily contrasted with those obtained in a real plant. Initially, we compare the PID (proportional–integral–derivative) models used in previous studies for the optimization of this type of plant with modeling using the multivariate adaptive regression splines (MARS) model.

Thermal Performance of Solar Tower Using Air as Heat Transfer Fluid under MENA Region Climate

2020 ◽  
Author(s):  
Sara EL Hassani ◽  
Hanane AIT Lahoussine Ouali ◽  
Benyounes Raillani ◽  
Mohammed Amine Moussaoui ◽  
Ahmed Mezrhab ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Transfer Fluid ◽  
Mena Region

A General Model for Analyzing the Thermal Characteristics of a Class of Latent Heat Thermal Energy Storage Systems

1999 ◽  
Vol 121 (4) ◽  
pp. 185-193 ◽  
Author(s):  
Kang Yanbing ◽  
Zhang Yinping ◽  
Jiang Yi ◽  
Zhu Yingxin
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Latent Heat ◽  
Thermal Performance ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
General Model ◽  
Thermal Characteristics ◽  
System Structure ◽  
Heat Transfer Fluid

The present study describes and classifies latent heat thermal energy storage (LHTES) systems according to their structural characteristics. A general model is developed for analyzing the thermal characteristics of the various typical LHTES systems to simulate thermal characteristics such as instantaneous heat transfer rate, instantaneous thermal storage capacity, etc. of the various typical LHTES systems. The model can calculate some important but difficult to measure system parameters for monitoring the charging or discharging processes of the systems. The model is verified using experimental data in the literature. Results from the model can be used to discuss the influence of the characteristic geometric parameters of LHTES units, the physical properties of the phase change material (PCM), the flow type and the velocity of heat transfer fluid (HTF) on the system thermal performance and to identify the key factors influencing the system thermal performance. The general model can be used to select and optimize the system structure and to simulate the thermal behavior of various typical LHTES systems.

scholarly journals Heat Transfer Augmentation of Concentrated Solar Absorber Using Modified Surface Contour

2021 ◽  
Vol 11 (1) ◽  
pp. 24-33
Author(s):  
Ramalingam Senthil ◽  
Arvind Chezian ◽  
Zackir Hussain Ajmal Arsath
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Cavity Surface ◽  
Solar Absorbers ◽  
Surface Contour ◽  
Parabolic Dish ◽  
Plain Surface ◽  
Surface Modified

This work aims to compare the cavity surface contour’s thermal performance to that of the solar absorber’s plain surface contour for Scheffler type parabolic dish collectors. The absorber is tested for the temperature range up to 600°C without working fluid and 180°C with the working fluid. The modified absorber surface's thermal performance is compared with the flat surface absorber with and without heat transfer fluid. The peak temperature reached by the surface modified absorber (534°C) is about 8.6% more than that of the unmodified absorber (492°C) during an outdoor test without fluid. The energy efficiency of cavity surface absorber and plain surface absorber are 67.65% and 61.84%, respectively. The contoured cavity surface produces a more uniform temperature distribution and a higher heat absorption rate than the plain surface. The results are beneficial to the design of high-temperature solar absorbers for concentrated solar collectors.

scholarly journals Experimental Investigation on Thermal Performance of Double-U-tube Heat Exchanger Using CuO/water Nanofluid as Heat Transfer Fluid

2020 ◽  
Vol 165 ◽  
pp. 01022
Author(s):  
Ruiqing Du ◽  
Dandan Jiang ◽  
Yong Wang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Performance ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Heat Transfer Fluid ◽  
Geothermal Heat ◽  
Tube Heat Exchanger ◽  
Heating And Cooling ◽  
Geothermal Heat Exchanger

By applying the shallow ground energy to supply building heating and cooling, the geothermal heat exchanger systems were considered as an energy-efficient building service system. In this study, the CuO/water nanofluid was employed as circuit fluids of the geothermal heat exchanger system, and the thermal performance of the heat exchanger was investigated. The results showed that the heat transfer process of CuO/water nanofluid became stable earlier than that water. Furthermore, the heat transfer rate of nanofluid was higher than that of water when the heat transfer process plateaued.

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