Improving thermal efficiency of hydrate-based heat engine generating renewable energy from low-grade heat sources using a crystal engineering approach

Energy ◽  
2020 ◽  
Vol 198 ◽  
pp. 117403
Author(s):  
Ryo Koyama ◽  
Li-Jen Chen ◽  
Saman Alavi ◽  
Ryo Ohmura
Keyword(s):  
Renewable Energy ◽  
Thermal Efficiency ◽  
Crystal Engineering ◽  
Heat Engine ◽  
Low Grade ◽  
Heat Sources ◽  
Engineering Approach ◽  
Low Grade Heat

scholarly journals Optimization of a Thermomagnetic Heat Engine for Harvesting Low Grade Thermal Energy

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5768
Author(s):  
Zeeshan ◽  
Muhammad Uzair Mehmood ◽  
Sungbo Cho
Keyword(s):  
Thermal Energy ◽  
Heat Engine ◽  
Integrated Approach ◽  
Heat Transfer Fluid ◽  
Low Grade ◽  
Heat Sources ◽  
Energy Harvesters ◽  
Output Performance ◽  
Depth Analysis ◽  
Low Grade Heat

Thermomagnetic energy harvesters are one form of technology that can be effectively used to extract energy from low grade heat sources, without causing damage to the environment. In this study, we investigated the output performance of our previously designed thermomagnetic heat engine, which was developed to extract thermal energy by exploiting the magnetocaloric effect of gadolinium. The proposed heat engine uses water as the heat transfer fluid, with heat sources at a temperature in the range 20–65 °C. Although this method turned out to be a promising solution to extract thermal energy, the amount of energy extracted through this geometry of thermomagnetic engine was limited and depends on the interaction between magnetic flux and magnetocaloric material. Therefore, in this paper we carry out an in-depth analysis of the designed thermomagnetic heat engine with an integrated approach of numerical simulation and experimental validation. The computational model improved recognition of the critical component to developing an optimized model of the thermomagnetic heat engine. Based on the simulation result, a new working model was developed that showed a significant improvement in the rpm and axial torque generation. The results indicate that the peak RPM and torque of the engine are improved by 34.3% and 32.2%, respectively.

Energy Storage and Waste Heat Recovery: A Synergistic Effect Benefiting Renewable Energy

2011 ◽  
Author(s):  
Richard B. Peterson ◽  
Robbie Ingram-Goble ◽  
Kevin J. Harada ◽  
Hailei Wang
Keyword(s):  
Renewable Energy ◽  
Energy Storage ◽  
Heat Pump ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Heat Engine ◽  
Low Grade ◽  
Round Trip ◽  
Low Grade Heat

In order for renewable energy to displace 20% or more of the conventional power generating base without depending on significant hot spinning reserves, reliable and cost effective energy storage will be needed at the utility scale. Developing and deploying practical energy storage at this level is a major challenge and no single technology appears to have a dominant position. Storing electrical energy by way of thermal storage at moderate-to-low temperatures has not received much attention in the past. In fact, the conventional thinking is that heat pump/heat engine mediated energy storage is too inefficient (round trip efficiency of 30% or lower) to be practical. However, an innovative and efficient storage approach is proposed in this paper by incorporating sensible heat storage in a Rankine-type heat pump/heat engine cycle to increase the round trip efficiency. Furthermore, by using a source of waste (or otherwise low-grade) heat, round trip efficiencies can be enhanced further. Currently, there appears to be no significant linkage between waste heat recovery and grid-level energy storage, although the market opportunity for each is considerable. Using the thermal approach described here, a system can be created that uses very low-grade heat in the range between 50 to 70 °C. Furthermore, conventional technology can be used to implement the system where no extreme conditions are present anywhere in the cycle. Hence, it is thought to have advantages over other energy storage concepts being developed.

Meanline Analysis and CFD Study of a Radial Inflow Turbine With Vaneless Distributor for Low Temperature Organic Rankine Cycle

2020 ◽  
Author(s):  
M. Deligant ◽  
S. Braccio ◽  
T. Capurso ◽  
F. Fornarelli ◽  
M. Torresi ◽  
...  
Keyword(s):  
Energy Demand ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Low Grade ◽  
Heat Sources ◽  
Turbine Wheel ◽  
Good Efficiency ◽  
Low Grade Heat

Abstract The Organic Rankine Cycle (ORC) allows the conversion of low-grade heat sources into electricity. Although this technology is not new, the increase in energy demand and the need to reduce CO2 emissions create new opportunities to harvest low grade heat sources such as waste heat. Radial turbines have a simple construction, they are robust and they are not very sensitive to geometry inaccuracies. Most of the radial inflow turbines used for ORC application feature a vaned nozzle ensuring the appropriate distribution angle at the rotor inlet. In this work, no nozzle is considered but only the vaneless gap (distributor). This configuration, without any vaned nozzle, is supposed to be more flexible under varying operating conditions with respect to fixed vanes and to maintain a good efficiency at off-design. This paper presents a performance analysis carried out by means of two approaches: a combination of meanline loss models enhanced with real gas fluid properties and 3D CFD computations, taking into account the entire turbomachine including the scroll housing, the vaneless gap, the turbine wheel and the axial discharge pipe. A detailed analysis of the flow field through the turbomachine is carried out, both under design and off design conditions, with a particular focus on the entropy field in order to evaluate the loss distribution between the scroll housing, the vaneless gap and the turbine wheel.

scholarly journals Comparative Thermodynamic Analysis of Kalina and Kalina Flash Cycles for Utilizing Low-Grade Heat Sources

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3311 ◽  
Author(s):  
Kyoung Kim ◽  
Chul Han ◽  
Hyung Ko
Keyword(s):  
Mass Fraction ◽  
Power Production ◽  
Low Grade ◽  
Heat Sources ◽  
Kalina Cycle ◽  
Thermodynamic Performance ◽  
Locally Maximal ◽  
The Difference ◽  
Proposed Modification ◽  
Low Grade Heat

The Kalina flash cycle (KFC) is a novel, recently proposed modification of the Kalina cycle (KC) equipped with a flash vessel. This study performs a comparative analysis of the thermodynamic performance of KC and KFC utilizing low-grade heat sources. How separator pressure, flash pressure, and ammonia mass fraction affect the system performance is systematically and parametrically investigated. Dependences of net power and cycle efficiencies on these parameters as well as the mass flow rate, heat transfer rate and power production at the cycle components are analyzed. For a given set of separator pressure and ammonia mass fraction, there exists an optimum flash pressure making exergy efficiency locally maximal. For these pressures, which are higher for higher separator pressure and lower ammonia mass fraction, KFC shows better performance than KC both in net power and cycle efficiencies. At higher ammonia mass fraction, however, the difference is smaller. While the maximum power production increases with separator pressure, the dependence is quite weak for the maximum values of both efficiencies.

Thermolytic osmotic heat engine for low-grade heat harvesting: Thermodynamic investigation and potential application exploration

2020 ◽  
Vol 259 ◽  
pp. 114192
Author(s):  
Xin Tong ◽  
Su Liu ◽  
Junchen Yan ◽  
Osvaldo A. Broesicke ◽  
Yongsheng Chen ◽  
...  
Keyword(s):  
Potential Application ◽  
Heat Engine ◽  
Low Grade ◽  
Thermodynamic Investigation ◽  
Low Grade Heat

scholarly journals Cool Steam Method for Desalinating Seawater

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2385
Author(s):  
Pedro Arnau ◽  
Naeria Navarro ◽  
Javier Soraluce ◽  
Jose Martínez-Iglesias ◽  
Jorge Illas ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Heat Source ◽  
Latent Heat ◽  
Heat Sink ◽  
Low Grade ◽  
Heat Sources ◽  
Working Pressure ◽  
Multi Stage ◽  
Heat Of Evaporation ◽  
Low Grade Heat

Cool steam is an innovative distillation technology based on low-temperature thermal distillation (LTTD), which allows obtaining fresh water from non-safe water sources with substantially low energy consumption. LTTD consists of distilling at low temperatures by lowering the working pressure and making the most of low-grade heat sources (either natural or artificial) to evaporate water and then condensate it at a cooler heat sink. To perform the process, an external heat source is needed that provides the latent heat of evaporation and a temperature gradient to maintain the distillation cycle. Depending on the available temperature gradient, several stages can be implemented, leading to a multi-stage device. The cool steam device can thus be single or multi-stage, being raw water fed to every stage from the top and evaporated in contact with the warmer surface within the said stage. Acting as a heat carrier, the water vapor travels to the cooler surface and condensates in contact with it. The latent heat of condensation is then conducted through the conductive wall to the next stage. Net heat flux is then established from the heat source until the heat sink, allowing distilling water inside every parallel stage.

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