scholarly journals Solar Salt Latent Heat Thermal Storage for a Small Solar Organic Rankine Cycle Plant

2018 ◽  
Author(s):  
Sol-Carolina Costa ◽  
Khamid Mahkamov ◽  
Murat Kenisarin ◽  
Kevin Lynn ◽  
Elvedin Halimic ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Latent Heat ◽  
Storage System ◽  
Organic Rankine Cycle ◽  
Heat Pipes ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Working Fluid ◽  
External Diameter ◽  
Solar Salt

The design of the Latent Heat Thermal Storage System (LHTESS) was developed with thermal capacity of about 100 kWh as a part of small solar plant, based on the Organic Rankine Cycle (ORC). The phase change material (PCM) used is Solar salt with the melting/solidification temperature of about 220°C. Thermo-physical properties of the PCM were measured, including its phase transition temperature, heat of fusion, specific heat and thermal conductivity. The design of the thermal storage was finalized by means of the 3-D CFD analysis. The thermal storage system is made of six rectangular boxes with dimensions of 1 m (width) × 0.66 m (height) × 0.47 m (depth). The thermal energy is delivered to each of the thermal storage boxes with the use of thermal oil, heated by Fresnel mirrors. The heat is transferred into and from the PCM in the box using 40 bi-directional heat pipes with the external diameter of about 12 mm. The length of the heat pipe in the PCM box is 430 mm and it is placed in the cylindrical metallic protection cartridge, installed in the thermal storage vessel. The working fluid in the heat pipe is water. A set of metallic screens are installed in the box with the pitch of 8–10 mm to enhance the heat transfer from heat pipes to the PCM and vice-versa during the charging and discharging processes, which take about 4 hours. The one unit of the described thermal storage system is undergoing the laboratory tests. Preliminary results demonstrate that the performance of the thermal storage is in a good agreement with numerical predictions. After completion of final design modifications, all units will be assembled at the plant’s demonstration site and tested with the ORC turbine.

scholarly journals Solar Salt Latent Heat Thermal Storage for a Small Solar Organic Rankine Cycle Plant

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Sol-Carolina Costa ◽  
Khamid Mahkamov ◽  
Murat Kenisarin ◽  
Mohammad Ismail ◽  
Kevin Lynn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Latent Heat ◽  
Storage System ◽  
Organic Rankine Cycle ◽  
Heat Pipes ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Thermal Bonding ◽  
Solar Salt ◽  
Computational Fluid Dynamics Analysis

Abstract The design of the latent heat thermal storage system (LHTESS) was developed with a thermal capacity of about 100 kW h as a part of small solar plant based on the organic Rankine cycle (ORC). The phase change material (PCM) used is solar salt with the melting/solidification temperature of about 220 °C. Thermophysical properties of the PCM were measured, including its phase transition temperature, heat of fusion, specific heat, and thermal conductivity. The design of the thermal storage was finalized by means of the 3D computational fluid dynamics analysis. The thermal storage system is modular, and the thermal energy is delivered with the use of thermal oil, heated by Fresnel mirrors. The heat is transferred into and from the PCM in the casing using bidirectional heat pipes, filled with water. A set of metallic screens are installed in the box with the pitch of 8–10 mm to enhance the heat transfer from heat pipes to the PCM and vice-versa during the charging and discharging processes, which take about 4 h. This work presents a numerical study on the use of metallic fins without thermal bonding as a heat transfer enhancement method for the solar salt LHTESS. The results show that the absence of the thermal bonding between fins and heat pipes (there was a gap of 0.5 mm between them) did not result in a significant reduction of charging or discharging periods. As expected, aluminum fins provide better performance in comparison with steel ones due to the difference in the material conductivity. The main advantage observed for the case of using aluminum fins was the lower temperature gradient across the LHTESS.

Numerical and Experimental Analysis of a PCM Thermal Storage System

2014 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda
Keyword(s):  
Latent Heat ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage System ◽  
District Heating ◽  
Thermal Storage ◽  
Working Fluid ◽  
Latent Heat Storage ◽  
Thermal Enhancement ◽  
Charging And Discharging Processes

Phase-change materials (PCM) are particularly promising for thermal storage in energy systems where the working fluid is either characterized by small specific heat or small temperature difference. In these cases, sensible heat storage would involve small energy densities (i.e. energy per unit volume). Latent heat storage would allow one to reduce the volume of storage tanks, but also reduce problems related with thermal stratification. On the other hand, heat transfer in PCMs needs to be enhanced in order to complete the charging and discharging processes in reasonable time. This paper reports the numerical and experimental activity performed by the authors related with the design of latent heat storage systems for district heating applications. Among the various enhancement methods, fins present some technical advantages related with manufacturing and management, which make them suitable for the application in district heating systems. The following aspects are considered in this paper: 1) melting and solidification; 2) modeling approaches and validation; 3) thermal enhancement with circular, radial or Y-shaped fins.

scholarly journals Development of a Small Solar Thermal Power Plant for Heat and Power Supply to Domestic and Small Business Buildings

2018 ◽  
Author(s):  
Khamid Mahkamov ◽  
Piero Pili ◽  
Roberto Manca ◽  
Arthur Leroux ◽  
Andre Charles Mintsa ◽  
...  
Keyword(s):  
Power Plant ◽  
Latent Heat ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Solar Thermal ◽  
Solar Thermal Power ◽  
Solar Field

The small solar thermal power plant is being developed with funding from EU Horizon 2020 Program. The plant is configured around a 2-kWel Organic Rankine Cycle turbine and solar field, made of Fresnel mirrors. The solar field is used to heat thermal oil to the temperature of about 240 °C. This thermal energy is used to run the Organic Rankine Cycle turbine and the heat rejected in its condenser (about 18-kWth) is utilized for hot water production and living space heating. The plant is equipped with a latent heat thermal storage to extend its operation by about 4 hours during the evening building occupancy period. The phase change material used is Solar salt with the melting/solidification point at about 220 °C. The total mass of the PCM is about 3,800 kg and the thermal storage capacity is about 100 kWh. The operation of the plant is monitored by a central controller unit. The main components of the plant are being manufactured and laboratory tested with the aim to assemble the plant at the demonstration site, located in Catalonia, Spain. At the first stage of investigations the ORC turbine will be directly integrated with the solar filed to evaluate their joint performance. During the second stage of tests, the Latent Heat Thermal Storage will be incorporated into the plant and its performance during the charging and discharging processes will be investigated. It is planned that the continuous filed tests of the whole plant will be performed during the 2018–2019 period.

scholarly journals Effect of Phase Change Material Storage on the Dynamic Performance of a Direct Vapor Generation Solar Organic Rankine Cycle System

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5904
Author(s):  
Jahan Zeb Alvi ◽  
Yongqiang Feng ◽  
Qian Wang ◽  
Muhammad Imran ◽  
Lehar Asip Khan ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Storage Tank ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Working Fluid ◽  
Vapor Generation ◽  
Cycle System ◽  
Change Material

Solar energy is a potential source for a thermal power generation system. A direct vapor generation solar organic Rankine cycle system using phase change material storage was analyzed in the present study. The overall system consisted of an arrangement of evacuated flat plate collectors, a phase-change-material-based thermal storage tank, a turbine, a water-cooled condenser, and an organic fluid pump. The MATLAB programming environment was used to develop the thermodynamic model of the whole system. The thermal storage tank was modeled using the finite difference method and the results were validated against experimental work carried out in the past. The hourly weather data of Karachi, Pakistan, was used to carry out the dynamic simulation of the system on a weekly, monthly, and annual basis. The impact of phase change material storage on the enhancement of the overall system performance during the charging and discharging modes was also evaluated. The annual organic Rankine cycle efficiency, system efficiency, and net power output were observed to be 12.16%, 9.38%, and 26.8 kW, respectively. The spring and autumn seasons showed better performance of the phase change material storage system compared to the summer and winter seasons. The rise in working fluid temperature, the fall in phase change material temperature, and the amount of heat stored by the thermal storage were found to be at a maximum in September, while their values became a minimum in February.

scholarly journals Simulation of the Part Load Behavior of Combined Heat Pump-Organic Rankine Cycle Systems

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3870
Author(s):  
Bernd Eppinger ◽  
Mustafa Muradi ◽  
Daniel Scharrer ◽  
Lars Zigan ◽  
Peter Bazan ◽  
...  
Keyword(s):  
Heat Pump ◽  
Mass Flow ◽  
Thermal Energy ◽  
Renewable Energy Sources ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Working Fluid ◽  
Part Load ◽  
Load Behavior

Pumped Thermal Energy Storages (PTES) are suitable for bridging temporary energy shortages, which may occur due to the utilization of renewable energy sources. A combined heat pump (HP)-Organic Rankine Cycle (ORC) system with suitable thermal storage offers a favorable way to store energy for small to medium sized applications. To address the aspect of flexibility, the part load behavior of a combined HP-ORC system, both having R1233zd(E) (Trans-1-chloro-3,3,3-trifluoropropene) as working fluid and being connected through a water filled sensible thermal energy storage, is investigated using a MATLAB code with integration of the fluid database REFPROP. The influence on the isentropic efficiency of the working machines and therefore the power to power efficiency (P2P) of the complete system is shown by variation of the mass flow and a temperature drop in the thermal storage. Further machine-specific parameters such as volumetric efficiency and internal leakage efficiency are also considered. The results show the performance characteristics of the PTES as a function of the load. While the drop in storage temperature has only slight effects on the P2P efficiency, the reduction in mass flow contributes to the biggest decrease in the efficiency. Furthermore, a simulation for dynamic load analysis of a small energy grid in a settlement is conducted to show the course of energy demand, supplied energy by photovoltaic (PV) systems, as well as the PTES performance indicators throughout an entire year. It is shown that the use of PTES is particularly useful in the period between winter and summer time, when demand and supplied photovoltaic energy are approximately equal.

scholarly journals Experimental investigation of heat pipe thermal performance with microgrooves fabricated by wire electrical discharge machining

2020 ◽  
Vol 24 (2 Part A) ◽  
pp. 701-711
Author(s):  
Nishida Baptista ◽  
Larissa Krambeck ◽  
Dos Dias ◽  
Alves Antonini
Keyword(s):  
Heat Pipe ◽  
Thermal Performance ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Heat Pipes ◽  
Experimental Results ◽  
Working Fluid ◽  
Wire Electrical Discharge Machining ◽  
External Diameter ◽  
Wire Edm

This work presents the use of electrical discharge machining (EDM) technology for manufacturing of three different types of axial microgrooves in heat pipes. This specific process, called wire electrical discharge machining (wire-EDM), allows the fabrication of microgrooves on the inner wall of a heat pipe with accuracy. Different from other capillary structures, such as composite wick and screen mesh, the material is removed from the pipe?s container in order to conceive the capillary structure, which contributes with the mass reduction of the passive two-phase heat transfer device. The heat pipes were manufactured from a straight copper pipe with the external diameter of 9.45 mm, the inner diameter of 6.20 mm, and a total length of 200 mm. Three types of axial microgrooves were manufactured for constant width (35 ?m) and varying the depth (from 30-48 ?m), and thickness (from 35-70 ?m). The number of microgrooves was also varied from 21-32 microgrooves. Water was used as the working fluid and the loading filling ratio was 60% of the evaporator volume. The condenser was cooled by air forced convection, the adiabatic section was insulated and the evaporator was heated by an electrical resistor and it was insulated from the environment with aeronautic thermal insulation. The thermal performance of the heat pipes are analyzed based on experimental results, so the heat pipes were tested at the horizontal and different inclinations under different low heat loads (from 5-50 W or a heat flux from 0.21-2.10 W/cm2). The experimental results showed that the axial microgrooves manufactured by the wire-EDM process worked satisfactorily in all analyzed cases and microgrooves of Type 1 showed a better thermal performance when compared with the others.

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