scholarly journals Selection of low temperature thermal power cycles

2020 ◽  
pp. 165-165
Author(s):  
Mukundjee Pandey ◽  
Biranchi Padhi ◽  
Ipsita Mishra
Keyword(s):  
Low Temperature ◽  
Thermal Energy ◽  
High Efficiency ◽  
Thermal Power ◽  
Organic Rankine Cycle ◽  
Operating Conditions ◽  
Solar Thermal ◽  
Heat Extraction ◽  
Solar Thermal Energy ◽  
Kalina Cycle

In today?s world, we are facing the problem of fossil fuel depletion along with its cost continuously increasing. Also, it is getting difficult to live in a pollution free environment. Solar energy is one of the most abundantly and freely available form of energy. Out of the various ways to harness solar en-ergy, solar thermal energy is the most efficient as compared to photo-voltaic technology. There are various cycles to convert the solar thermal energy to mechanical work, but Kalina cycle (KC) is one of the best candidates for high efficiency considerations. Therefore, the authors have proposed a novel KC having the double separator arrangements to increase the amount of ammonia vapors at the inlet of turbine, and hence have tried to minimize the pumping power for Double Separator Kalina Cycle (DS-KC) by reducing the fraction of gas/vapors through it. Here, in this paper we have tried to com-pare Organic Rankine Cycle (ORC), Brayton Cycle (BC) and Double Sepa-rator Kalina Cycle (DS-KC) for low temperature heat extraction from para-bolic trough collectors having arc-circular plug with slits (PTC). The effect of different operating conditions; like the number of PTCs, mass flow rate of fluids in different cycles, pressure difference in turbine are analyzed. The ef-fect of these different operating conditions on different parameters like net work done, heat lost by condenser, thermal efficiency and installation cost per unit kW for DS-KC, ORC and BC are studied.

Pyrazolium Phase Change Materials for Solar-Thermal and Wind Energy Storage

2019 ◽  
Author(s):  
Karolina Matuszek ◽  
R. Vijayaraghavan ◽  
Craig Forsyth ◽  
Surianarayanan Mahadevan ◽  
Mega Kar ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
High Efficiency ◽  
Scale Up ◽  
Solar Thermal ◽  
Energy Storage Materials ◽  
Solar Thermal Energy ◽  
Storage Materials

Renewable energy has the ultimate capacity to resolve the environmental and scarcity challenges of the world’s energy supplies. However, both the utility of these sources and the economics of their implementation are strongly limited by their intermittent nature; inexpensive means of energy storage therefore needs to be part of the design. Distributed thermal energy storage is surprisingly underdeveloped in this context, in part due to the lack of advanced storage materials. Here, we describe a novel family of thermal energy storage materials based on pyrazolium cation, that operate in the 100-220°C temperature range, offering safe, inexpensive capacity, opening new pathways for high efficiency collection and storage of both solar-thermal energy, as well as excess wind power. We probe the molecular origins of the high thermal energy storage capacity of these ionic materials and demonstrate extended cycling that provides a basis for further scale up and development.

scholarly journals Energy Analysis of a Novel Ejector-Compressor Cooling Cycle Driven by Electricity and Heat (Waste Heat or Solar Energy)

2020 ◽  
Vol 12 (19) ◽  
pp. 8178
Author(s):  
Fahid Riaz ◽  
Kah Hoe Tan ◽  
Muhammad Farooq ◽  
Muhammad Imran ◽  
Poh Seng Lee
Keyword(s):  
Low Temperature ◽  
Thermal Energy ◽  
Waste Heat ◽  
Solar Thermal ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Low Grade ◽  
Solar Thermal Energy ◽  
Temperature Heat ◽  
Vapour Compression

Low-grade heat is abundantly available as solar thermal energy and as industrial waste heat. Non concentrating solar collectors can provide heat with temperatures 75–100 °C. In this paper, a new system is proposed and analyzed which enhances the electrical coefficient of performance (COP) of vapour compression cycle (VCC) by incorporating low-temperature heat-driven ejectors. This novel system, ejector enhanced vapour compression refrigeration cycle (EEVCRC), significantly increases the electrical COP of the system while utilizing abundantly available low-temperature solar or waste heat (below 100 °C). This system uses two ejectors in an innovative way such that the higher-pressure ejector is used at the downstream of the electrically driven compressor to help reduce the delivery pressure for the electrical compressor. The lower pressure ejector is used to reduce the quality of wet vapour at the entrance of the evaporator. This system has been modelled in Engineering Equation Solver (EES) and its performance is theoretically compared with conventional VCC, enhanced ejector refrigeration system (EERS), and ejection-compression system (ECS). The proposed EEVCRC gives better electrical COP as compared to all the three systems. The parametric study has been conducted and it is found that the COP of the proposed system increases exponentially at lower condensation temperature and higher evaporator temperature. At 50 °C condenser temperature, the electrical COP of EEVCRC is 50% higher than conventional VCC while at 35 °C, the electrical COP of EEVCRC is 90% higher than conventional VCC. For the higher temperature heat source, and hence the higher generator temperatures, the electrical COP of EEVCRC increases linearly while there is no increase in the electrical COP for ECS. The better global COP indicates that a small solar collector will be needed if this system is driven by solar thermal energy. It is found that by using the second ejector at the upstream of the electrical compressor, the electrical COP is increased by 49.2% as compared to a single ejector system.

Experimental investigation of methanol decomposition with mid- and low-temperature solar thermal energy

2010 ◽  
Vol 35 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Jun Sui ◽  
Qibin Liu ◽  
Jianguo Dang ◽  
Dong Guo ◽  
Hongguang Jin ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Low Temperature ◽  
Thermal Energy ◽  
Methanol Decomposition ◽  
Solar Thermal ◽  
Solar Thermal Energy

System and component modelling of a low temperature solar thermal energy conversion cycle

2013 ◽  
Vol 24 (4) ◽  
pp. 51-62
Author(s):  
Shadreck M. Situmbeko ◽  
Freddie L. Inambao
Keyword(s):  
Low Temperature ◽  
Solar Energy ◽  
Thermal Energy ◽  
Electrical Power ◽  
Solar Thermal ◽  
Working Fluid ◽  
Small Scale ◽  
Solar Thermal Energy ◽  
Solar Field ◽  
Conversion Technology

Solar thermal energy (STE) technology refers to the conversion of solar energy to readily usable energy forms. The most important component of a STE technology is the collectors; these absorb the shorter wavelength solar energy (400-700nm) and convert it into usable, longer wavelength (about 10 times as long) heat energy. Depending on the quality (temperature and intensity) of the resulting thermal energy, further conversions to other energy forms such as electrical power may follow. Currently some high temperature STE technologies for electricity production have attained technical maturity; technologies such as parabolic dish (commercially available), parabolic trough and power tower are only hindered by unfavourable market factors including high maintenance and operating costs. Low temperature STEs have so far been restricted to water and space heating; however, owing to their lower running costs and almost maintenance free operation, although operating at lower efficiencies, may hold a key to future wider usage of solar energy. Low temperature STE conversion technology typically uses flat plate and low concentrating collectors such as parabolic troughs to harness solar energy for conversion to mechanical and/or electrical energy. These collector systems are relatively cheaper, simpler in construction and easier to operate due to the absence of complex solar tracking equipment. Low temperature STEs operate within temperatures ranges below 300oC. This research work is geared towards developing feasible low temperature STE conversion technology for electrical power generation. Preliminary small-scale concept plants have been designed at 500Wp and 10KWp. Mathematical models of the plant systems have been developed and simulated on the EES (Engineering Equation Solver) platform. Fourteen candidate working fluids and three cycle configurations have been analysed with the models. The analyses included a logic model selector through which an optimal conversion cycle configuration and working fluid mix was established. This was followed by detailed plant component modelling; the detailed component model for the solar field was completed and was based on 2-dimensional segmented thermal network, heat transfer and thermo fluid dynamics analyses. Input data such as solar insolation, ambient temperature and wind speed were obtained from the national meteorology databases. Detailed models of the other cycle components are to follow in next stage of the research. This paper presents findings of the system and solar field component.

Drying of Oil Palm Fronds Using Concentrated Solar Thermal Power

2014 ◽  
Vol 699 ◽  
pp. 449-454 ◽  
Author(s):  
Shaharin Anwar Sulaiman ◽  
Farid Fawzy Fathy Taha
Keyword(s):  
Thermal Energy ◽  
Oil Palm ◽  
Thermal Power ◽  
Solar Thermal ◽  
Drying Rate ◽  
Drying Methods ◽  
Solar Thermal Energy ◽  
Oil Palm Fronds ◽  
Electric Oven ◽  
Palm Fronds

Malaysia has great potential for biomass stock. The fact that oil palm fronds contain high moisture content makes it unsuitable to be used directly as a biomass fuel neither for direct combustion nor gasification. Conventional and costly drying methods make the fronds a non-attractive fuel especially in humid tropical countries, where sources of biomass is abundant. A new solar dryer design is proposed that utilizes concentrated solar thermal energy for drying oil palm fronds. A prototype for the dryer has been fabricated and tested. The system’s target is to maximize the thermal energy received by the system and to minimize energy loss out of the system. Experiments were performed on samples of oil palm fronds at a drying temperature not exceeding 110°C; in order not to affect the organic material of the biomass. Results were compared with another experiment performed at the same temperature. An electric oven was used for drying. The samples were completely dried using the proposed system for 6.5 hours, compared to 10.5 hours by using the electric oven. The proposed system achieved an average drying rate of 4.75 g/hr compared to an average drying rate of 2.83 g/hr using the electric oven. The efficiency of the dryer was calculated to be 55.4%, implying good potential of the proposed system.

Mechanism of Upgrading Low-Grade Solar Thermal Energy and Experimental Validation

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Hui Hong ◽  
Hongguang Jin ◽  
Jun Sui ◽  
Jun Ji
Keyword(s):  
Energy Level ◽  
Thermal Energy ◽  
Power Plants ◽  
Thermal Power ◽  
Chemical Energy ◽  
Solar Thermal ◽  
Low Grade ◽  
Thermal Power Plants ◽  
Solar Thermal Energy ◽  
Middle Temperature

Solar thermochemical processes inherently included the conversion of solar thermal energy into chemical energy. In this paper, a new mechanism of upgrading the energy level of solar thermal energy at around 200°C was revealed based on the second law thermodynamics and was then experimentally proven. An expression was derived to describe the upgrading of the energy level from low-grade solar thermal energy to high-grade chemical energy. The resulting equation explicitly reveals the interrelations of energy levels between middle-temperature solar thermal energy and methanol fuel, and identifies the interactions of mean solar flux and the reactivity of methanol decomposition. The proposed mechanism was experimentally verified by using the fabricated 5kW prototype of the receiver∕reactor. The agreement between the theoretical and the experimental results proves the validity of the mechanism for upgrading the energy level of low-grade solar thermal energy by integrating clean synthetic fuel. Moreover, the application of this new middle-temperature solar∕methanol hybrid thermochemical process into a combined cycle is expected to have a net solar-to-electric efficiency of about 27.8%, which is competitive with other solar-hybrid thermal power plants using high-temperature solar thermal energy. The results obtained here indicate the possibility of utilizing solar thermal energy at around 200°C for electricity generation with high efficiency by upgrading the energy level of solar thermal energy, and provide an enhancement to solar thermal power plants with the development of this low-grade solar thermochemical technology in the near future.

Numerical Simulation & Experimental Research of Heat Charging Process of Cylindrical Units with PCM of Al-Si Alloy

2010 ◽  
Vol 171-172 ◽  
pp. 223-228
Author(s):  
Guan Sheng Chen ◽  
Ren Yuan Zhang ◽  
Feng Li ◽  
Shi Dong Li ◽  
Li Zhang
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermal Power ◽  
Test System ◽  
Solar Thermal ◽  
Experimental Result ◽  
Solar Thermal Energy ◽  
Storage Unit

Phase change thermal storage used metal as phase change material (PCM) is an important mode of solar thermal energy storage. In this paper, the heat charging processes of solar heating units were simulated under three kinds of heating flux 100,150 and 200kW/m2 at the bottom face respectively, while the thickness of heat receiving layer at the bottom was in 5, 10 and 15mm. Al-Si alloy was selected as PCM used in the cylindrical body of the units which were in the size of φ1000×1000mm. The change of temperature and solid-liquid phase change interface of Al-Si alloy were analyzed to find out the suitable absorber thickness of thermal energy storage units which can run safety under the condition of temperature 700~900K and heat flux 100~200kW/m2, such as the application of solar thermal energy storage unit in high temperature solar thermal power stations. In the last a test system was built up and the experimental result was close to the simulation value of a unit in the size of φ300×1000×10mm.

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