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

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.

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.

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.

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