scholarly journals High Performance Cascading Adsorption Refrigeration Cycle with Internal Heat Recovery Driven by a Low Grade Heat Source Temperature

Energies ◽  
2009 ◽  
Vol 2 (4) ◽  
pp. 1170-1191 ◽  
Author(s):  
Aep Saepul Uyun ◽  
Takahiko Miyazaki ◽  
Yuki Ueda ◽  
Atsushi Akisawa
Keyword(s):  
Heat Source ◽  
Heat Recovery ◽  
High Performance ◽  
Internal Heat ◽  
Low Grade ◽  
Refrigeration Cycle ◽  
Adsorption Refrigeration ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Low Grade Heat

scholarly journals Parametric Study of a Supercritical CO2 Power Cycle for Waste Heat Recovery with Variation in Cold Temperature and Heat Source Temperature

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6648
Author(s):  
Young-Min Kim ◽  
Young-Duk Lee ◽  
Kook-Young Ahn
Keyword(s):  
Heat Source ◽  
Thermal Efficiency ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Low Pressure ◽  
Power Cycle ◽  
Cooling Temperature ◽  
Source Temperature ◽  
Heat Source Temperature

The supercritical carbon dioxide (S-CO2) power cycle is a promising development for waste heat recovery (WHR) due to its high efficiency despite its simplicity and compactness compared with a steam bottoming cycle. A simple recuperated S-CO2 power cycle cannot fully utilize the waste heat due to the trade-off between the heat recovery and thermal efficiency of the cycle. A split cycle in which the working fluid is preheated by the recuperator and the heat source separately can be used to maximize the power output from a given waste heat source. In this study, the operating conditions of split S-CO2 power cycles for waste heat recovery from a gas turbine and an engine were studied to accommodate the temperature variation of the heat sink and the waste heat source. The results show that it is vital to increase the low pressure of the cycle along with a corresponding increase in the cooling temperature to maintain the low-compression work near the critical point. The net power decreases by 6 to 9% for every 5 °C rise in the cooling temperature from 20 to 50 °C due to the decrease in heat recovery and thermal efficiency of the cycle. The effect of the heat-source temperature on the optimal low-pressure side was negligible, and the optimal high pressure of the cycle increased with an increase in the heat-source temperature. As the heat-source temperature increased in steps of 50 °C from 300 to 400 °C, the system efficiency increased by approximately 2% (absolute efficiency), and the net power significantly increased by 30 to 40%.

scholarly journals The CO2 Transcritical Power Cycle for Low Grade Heat Recovery: Discussion on Temperature Profiles in System Heat Exchangers

2011 ◽  
Author(s):  
Y. Chen ◽  
P. Lundqvist
Keyword(s):  
Carbon Dioxide ◽  
Heat Source ◽  
Temperature Profile ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Low Grade ◽  
Power Cycle ◽  
Low Grade Heat ◽  
Cycle Efficiency ◽  
Better Than

Carbon dioxide transcritical power cycle has many advantages in low-grade heat source recovery compared to conventional systems with other working fluids. This is mainly due to the supercritical CO2’s temperature profile can match the heat source temperature profile better than other pure working fluids and its heat transfer performance is better than the fluid mixtures, which enables a better cycle efficiency. Moreover, the specific heat of supercritical CO2 will have sharp variations in the region close to its critical point, which will create a concave shape temperature profile in the heat exchanger that used for recovering heat from low-grade heat sources. This brings more advantage to carbon dioxide transcritical power systems in low-grade heat recovery. This study discusses the advantage of carbon dioxide power system in low-grade heat source recovery by taking this effect into account. A basic carbon dioxide transcritical power system with an Internal Heat Exchanger (IHX) is employed for the analysis and the system performance is also compared with a basic Organic Rankin Cycle (ORC). Software Engineering Equation Solver (EES) and Refprop 7.0 are used for the cycle efficiency and working fluid properties calculations.

Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
High Performance ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Low Grade ◽  
Thermal Battery ◽  
Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

Efficient Co-Harvesting of Solar Energy and Low-Grade Heat by Molecular Photoswitches for High Energy Density, Long-Term Stable Solar Thermal Battery

2019 ◽  
Author(s):  
Zhao-Yang Zhang ◽  
Tao LI
Keyword(s):  
Energy Density ◽  
Solar Energy ◽  
High Performance ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
Low Grade ◽  
Thermal Battery ◽  
Low Grade Heat

Solar energy and ambient heat are two inexhaustible energy sources for addressing the global challenge of energy and sustainability. Solar thermal battery based on molecular switches that can store solar energy and release it as heat has recently attracted great interest, but its development is severely limited by both low energy density and short storage stability. On the other hand, the efficient recovery and upgrading of low-grade heat, especially that of the ambient heat, has been a great challenge. Here we report that solar energy and ambient heat can be simultaneously harvested and stored, which is enabled by room-temperature photochemical crystal-to-liquid transitions of small-molecule photoswitches. The two forms of energy are released together to produce high-temperature heat during the reverse photochemical phase change. This strategy, combined with molecular design, provides high energy density of 320-370 J/g and long-term storage stability (half-life of about 3 months). On this basis, we fabricate high-performance, flexible film devices of solar thermal battery, which can be readily recharged at room temperature with good cycling ability, show fast rate of heat release, and produce high-temperature heat that is >20<sup> o</sup>C higher than the ambient temperature. Our work opens up a new avenue to harvest ambient heat, and demonstrate a feasible strategy to develop high-performance solar thermal battery.

Sign in / Sign up

Export Citation Format

Share Document