Rankine Cycle Generator Research Articles

Experimental study on horizontal tube falling film evaporation in geothermal powered organic Rankine cycle generation

Geothermal energy has become one of the indispensable renewable energy in the energy development in the 21st century, and it is also one of the most realistic and competitive energy. The orc power generation test system with low temperature heat source (60 ∼ 90 °C) is designed, and the key component horizontal tube falling film evaporator is designed. The experimental results show that the heat transfer coefficient increases with the increase of evaporation temperature in the range of 40 ∼ 65 °C. The experimental results show that when the spray density is in the range of 0.010 ∼ 0.025 kg/m K, the heat transfer coefficient increases with the increase of spray density. The experimental results show that when the hot water mass flow rate is in the range of 0.06 ∼ 0.18 kg/s, the heat transfer coefficient increases with the increase of hot water mass flow rate.

Research of time-varying performance of solar distributed thermal-power plant with neutral network prediction

Solar energy is potential in the future, but until now its commercial application is limited due to its high price. Distributed solar thermal-power plant provides electricity and heat simultaneously to the nearby users. It is competitive with traditional power plant due to its improved efficiency and low price. In this paper, a unique distributed solar thermal-power plant is designed. It is located in Nanjing Chemical Industry Park in China. Its reliability and advantage are studied through theoretical simulation. The theoretical model consists of 6 modules: solar radiation, solar collectors, thermal energy storage tanks, heat hub, bioreactors and organic rankine cycle generator. The building and bioreactors play the roles of heat and electricity users, respectively. However, both the heat source and users are time-varying, which are especially harmful to the system due to its small scale. Therefore, a thermal energy storage system and a heat hub are applied to solve the problems. Furthermore, the research focuses on the contradiction between the time-varying load requirement and the real-time response of the heat hub. It is solved by applying neural network to predict the load requirement, which enables the system to work with proper operation parameters in real time. The probability model of prediction error is built to test the system reliability with Monte Carlo method. The simulation results show how the distributed solar thermal-power plant working with neural network satisfies the time-varying load requirement. While the load requirement varies from 4472 to 21638 kW during one day, the heat hub responds with heat transfer capacity from 5552 to 22272 kW. In most of the time, the temperature deviation rate of heat hub after optimization is lower than 0.03, and the corresponding bias due to prediction error is lower than 0.01.

Towards an off-grid fecal sludge treatment unit: demonstrating energy positive thermal treatment

Background: There is an unmet demand for community-scale fecal sludge treatment units (FSTUs) that serve communities of between 1,000 and 50,000 people and are able to operate in non-sewered and off-grid environments. An emerging industry standard for FSTUs includes as a key criteria energy independence in steady-state. Theoretically, there is sufficient thermal energy available in fecal sludge to provide the electrical power needed to run the FSTU. However, such a system had never been implemented. Methods: Biomass Controls has previously demonstrated the thermal treatment of fecal sludge using the Biogenic Refinery, a thermal FSTU deployed in three sites in India. In this article we describe testing where a Biogenic Refinery was paired with a thermal fluid heat exchanger and organic Rankine cycle generator to generate electrical power. Results: This Biogenic Refinery combined heat and power system generated sufficient electrical power to offset electrical parasitic loads in steady-state operation and produce a surplus of 1.2 kWe. Conclusions: The results of the study demonstrate that there is an excess of energy available and reliable mechanisms to generate electrical energy using an FSTU. Additional steps are necessary to transition to a true off-grid FSTU.

Towards an off-grid fecal sludge treatment unit: demonstrating energy positive thermal treatment.

Background: There is an unmet demand for community-scale fecal sludge treatment units (FSTUs) that serve communities of between 1,000 and 50,000 people and are able to operate in non-sewered and off-grid environments. An emerging industry standard for FSTUs includes as a key criteria energy independence in steady-state. Theoretically, there is sufficient thermal energy available in fecal sludge to provide the electrical power needed to run the FSTU. However, such a system had never been implemented. Methods: Biomass Controls has previously demonstrated the thermal treatment of fecal sludge using the Biogenic Refinery, a thermal FSTU deployed in three sites in India. In this article we describe testing where a Biogenic Refinery was paired with a thermal fluid heat exchanger and organic Rankine cycle generator to generate electrical power. Results: This Biogenic Refinery combined heat and power system generated sufficient electrical power to offset electrical parasitic loads in steady-state operation and produce a surplus of 1.2 kWe. Conclusions: The results of the study demonstrate that there is an excess of energy available and reliable mechanisms to generate electrical energy using an FSTU. Additional steps are necessary to transition to a true off-grid FSTU.

Evaluation on the Organic Rankine Cycle Generator Sets Firstly Applied in China’s Petrochemical Industry

The Organic Rankine Cycle (ORC) generator sets operated on the low-temperature waste heat device of an aromatics complex is the first demonstration set in the chinese petrochemical industry. By taking this set as an example, the paper introduced the circulation processes of the heating medium water and the ORC working medium in the low-temperature waste heat device. The author also summarized the process and equipment issues during the operation of the sets: in terms of process, improper design of bypass valves in the flow paths of hot water, control authority of the set is not available in DCS, and unstable generator loads under the influence of ambient temperature, etc.; in the field of equipment, bad equipment maintenance & repair as well as operability, manufacturing fault of KE710 generator, screw expander vibration, and loud running noise, etc. Exploring and solving the problems found in one cycle of the set operation are beneficial to the operation optimization of the ORC generator sets in the future. Therefore, the author proposed such solutions as redesigning the working medium circulating pump and using the latest and optimized screw expander, which resolved part of the problems as well as improved the reliability, maintainability and operability of the ORC generator sets. Through comparison between the calibration data and the operational data of the generator set under the same heat resources, it was found that the set’s operating load became less than its calibration load as the heat exchanger started to scale and the screw expander started to wear.

A techno-economic evaluation of a small-scale fluidized bed gasifier for solid recovered fuel

This paper reports a technical assessment for an air gasification plant for energy recovery from 5000t/y of a solid recovered fuel (SRF). This was obtained as one of the output streams from a sorting platform of municipal solid waste, which aims to minimize the utilization of the annexed landfill. The case study analysis was based on data provided by a pilot-scale bubbling fluidized bed gasifier, having a feedstock capacity of about 70kg/h of the obtained SRF. The tests indicate that the SRF can be converted into a syngas of valuable quality for energy applications. A plant configuration, which includes a bubbling fluidized bed reactor, a mild combustor, a 400kWe Organic Rankine Cycle generator and an air pollution control system, was defined and described in detail. The standard accounting items related to investment and operating costs were estimated on the basis of official manufacturer's specifications and information: they indicate an economic sustainability only in presence of an incentive tariff for energy production. A material flow analysis indicates that the implementation of the small-scale gasifier could allow a landfill volume saving of more than 10,000m3/y.

Demonstration of 10-Wp micro organic Rankine cycle generator for low-grade heat recovery

In this study, a μ-ORC (micro organic Rankine cycle) generator that produces net positive power from low-grade heat (i.e., temperature below 100 °C) was experimentally demonstrated. First, the basic performance of a 10-Wp μ-ORC prototype with a small originally developed displacement-type expander and state-of-the-art commercial DC (direct current) micro-pump was tested. The prototype μ-ORC was coupled with a DC generator to produce a net electrical power of 5 W without an external electricity supply. Finally, the components of the μ-ORC generator were packaged into a compact box to achieve a power density of 214 mW/L (volume), 293 mW/kg (weight), and 3.33 mW/cm2 (footprint), which are the best results achieved in the present study. The maximum achieved isentropic efficiencies of the expander and pump were 4.55% and 30.0%, respectively. There is much scope for further improvement of the power density. The present results suggest that a downscaled ORC generator could be used to recover the energy of widely distributed low-grade heat sources.

Recommendations for Energy Water Nexus Problems

The chronic water problems in parts of India are probably due mainly to mismanagement. The rolling blackout and brownout problems in the larger Indian cities are due to lack of generation capacity. Since about ninety percent of the world's electricity is generated based on the steam Rankine cycle, environmental water is necessary for cooling, and freshwater is used as the working fluid. Furthermore, electricity is tied to water as part of the bigger water energy nexus phenomena occurring worldwide. China has started and continued with many initiatives to correct problems with water management. Projects do exist where the climatically dry north is being fed water from the wet south. China has water energy nexus conditions occurring too. The review of the scientific literature on studies about the sources of the Ganges, the Yangtze, the Yellow river, the Indus and the Mekong (the drinking water source of about forty percent of the World's population), the glaciers that feed these sources and how they are shrinking with global warming, has yielded a simple policy decision. Mass balance considerations provide the answer that the logical solution of the recent accelerated water changing from solid to liquid on mountain tops, requires dams and storage areas (lakes) to prevent all that freshwater from escaping to the lowlands, and ultimately being discharged into the oceans. One of the other major contributions in this work is to suggest conversion of (old) Rankine cycle generation of electricity to (new) combined gas cycle generation and/or simple gas cycle generation. The combined gas cycle generation can achieve efficiencies of 55–60%, while that of the Rankine cycle power generation languishes around 30%. Less water is required per MW electric power generated for condenser cooling in the combined cycle. The simple gas cycle generation can achieve 40% thermal efficiency on the average and use no water for cooling. There is also the suggestion to upgrade to supercritical power plants due to the advances in power plant technologies. The improved thermal efficiencies gained from this upgrade generate other benefits as well. Another contribution is the suggestion to use seawater for closed system condenser cooling in power plants that are not near the sea or ocean or any large body of freshwater. The open system seawater condenser cooling has been practiced for years throughout the world. This will definitely reduce the demand for freshwater, which could otherwise be used for human consumption or agriculture. Additionally, the rising seas problem locally may be reduced somewhat if enough of the seawater is used.

A LNG Driven CCHP System with a Cold Energy Recovery Device

The CCHP system based on energy cascade utilization can get very high energy overall utilization efficiency. When LNG is used as the primary energy of a CCHP system, the higher efficiency can be obtained if the cold energy of LNG is recovered. Three CCHP systems integrated with LNG cold recovery facility are presented which are suitable for different situations. The thermodynamic calculation and analysis of the system consisting of combined cycle generating electricity, the LiBr absorption refrigeration units, the cryogenic Rankine cycle generation system and the cooling medium system were carried out. The results showed that the energy utility efficiency of the electricity generating was 34.78% and the total energy utility efficiency was up to 86.49%. This indicates that this technology have the potential to be employed in the industrial applications.