Solar low-pressure turbo-ejector Maisotsenko cycle-based power system for electricity, heating, cooling and distillation (original) (raw)
Related papers
Power, cool and water production by innovative cycles fed by solar energy
2015
The paper analyses complex arrangements for engines that can be engineered using Car Engine Turbocharger Technology. Such engines can be fed by concentrated solar energy, and are capable of producing Mechanical Power, Cool Power and Water concurrently. Ideal cycle analysis demonstrate a high rate of Solar Energy utilization for both mechanical power and cool power, as well as water production. An ideal Power fraction of thermal power from the sun over 50% can be expected. The maximum overall (mechanical and cool power) utilization factor of solar thermal power entering the engine is expected to be about twice the level of previous fractions.
Small-scale solar thermal Brayton cycle recuperator: experimental testing and heat loss analysis
5th Southern African Solar Energy Conference (SASEC2018), 2018
A small-scale solar thermal Brayton cycle (STBC) with open cavity receiver and air as working fluid is being developed at the University of Pretoria. A parabolic dish is utilised to concentrate solar irradiance. The cycle has been analysed and optimised to work with a simple receiver so that complexity and cost may be reduced. To achieve high cycle efficiencies and temperatures in the order of 730 °C, a large efficient recuperator has to be implemented especially since the proposed micro-turbine, an automotive turbocharger, cannot operate at high pressure ratios. The purpose of this research is to test a design for a low-pressure and high-temperature recuperator that can be implemented within the STBC, and can be locally manufactured for a relatively low cost since current solutions involve complex designs, expensive manufacturing processes and permanent joining methods that would eliminate the possibility for inspection and maintenance. The design is based on a clamped plate heat exchanger layout with a high temperature sealant. A small scale test-rig was built and experiments conducted. The data was used to verify the validity of a theoretical model which includes heat loss analysis. The test-rig did not perform optimally; however, a model validation was performed.
Overview of the Maisotsenko cycle – A way towards dew point evaporative cooling
The Maisotsenko Cycle (M-Cycle) is a thermodynamic conception which captures energy from the air by utilizing the psychrometric renewable energy available from the latent heat of water evaporating into the air. The cycle is well-known in the airconditioning (AC) field due to its potential of dew-point eva-porative cooling. However, its applicability has been recently expanded in several energy recovery applications. Therefore, the present study provides the overview of M-Cycle and its application in various heating, ventilation, and airconditioning (HVAC) systems; cooling systems; and gas turbine power cycles. Principle and features of the M-Cycle are discussed in comparison with conventional evaporative cooling, and consequently the thermodynamic limitation of the cycle is highlighted. It is reported that the standalone M-Cycle AC (MAC) system can achieve the AC load efficiently when the ambient air humidity is not so high regardless of ambient air temperature. Various modifications in MAC system design have been reviewed in order to investigate the M-Cycle applicability in humid regions. It is found that the hybrid, ejector, and desiccant based MAC systems enable a huge energy saving potential to achieve the sensible and latent load of AC in humid regions. Similarly, the overall system performance is significantly improved when the M-Cycle is utilized in cooling towers and evaporative condensers. Furthermore, the M-Cycle conception in gas turbine cycles has been realized recently in which the M-Cycle recuperator provides not only hot and humidified air for combustion but also recovers the heat from the turbine exhaust gases. The M-Cycle nature helps to provide the cooled air for turbine inlet air cooling and to control the pollution by reducing NO x formation during combustion. The study reviews three distinguished Maisotsenko gas turbine power cycles and their comparison with the conventional cycles, which shows the M-Cycle significance in power industry.
Solar Powered Ejector Cooling Cycle
Trans of the JSRAE, 2011
Non-chlorinated and fluorinated refrigeration system is desired from both viewpoints of global warming and ozone depletion problems as well as providing a system for utilizing renewable energy resource would be an important issue. Ejector cooling cycle is not a new original idea, while the cycle is possible to work without consuming fossil-energy resource and CO 2 emission when it works under solar energy. The major drawback of the cycle would be believed as its low energy conversion efficiency. It would not be academically true because the thermal efficiency of ejector-cooling cycle is given for heat input, while the COP of conventional heat-pump system is not based on heat input but on electricity input. This research will provide the useful information for developing a realistic ejector-cooling cycle from the analytical and experimental approaches. The results include the information on the best working fluid for the actual system and on an analytical method of performance as well as results of actual performance using an indoor testing apparatus.
Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle
International Journal of Refrigeration, 2011
This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle's wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 C to 23.88 C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 C where the optimum operation takes place.
International Journal of Energy Research, 2020
In this paper, a novel system to enhance the performance of a solar-driven finite speed alpha-type Stirling engine is proposed and evaluated. Part of the concentrated solar energy is used to drive an ejector refrigeration system. The cooling produced in the ejector cooling cycle is used to cool the Stirling engine to enhance its efficiency. Model equations to describe the systems are proposed and solved numerically. The results indicate that the new system produces averagely 3.3 times electrical power more than the conventional one. Moreover, the proposed system improves the Stirling engine efficiency by up to 46% in comparison with 19.15% for the conventional Stirling engine under solar radiation intensity of (1 kW/m 2). Also, the results showed that the solar radiation intensity and wind speed are the most influential parameters that affect the proposed system efficiency. The new system is recommended to use in desert climates where high average daily solar radiation intensity, low wind speeds, and water shortage exist. Economic analysis is carried out to determine the feasibility of the proposed system under different economic parameters. It is found that, for instance, the simple payback period is 4.64 years for the new system when the selling price of electricity is 0.35 $/kWh. K E Y W O R D S ejector cooling cycle, renewable energy, solar thermal utilization, Stirling engine 1 | INTRODUCTION Utilizing solar energy has become one of the priorities for many countries in the world because it is the key to energy security in the future. Unlike fossil fuels, solar energy is limitless and friendly to the environment. 1 The only challenge that faces us is to invite and develop new technologies that able to convert this free energy into useful forms of energy in a cost-efficient way. Over the last century, many solar energy systems were invented, manufactured, and developed, such as photovoltaic cells, solar collectors, solar desalination units, solar cooling cycles, and solar-driven Stirling engine. In 1819, Robert Stirling invited an engine that converts thermal energy into mechanical energy using a fixed amount of a compressible gas which compressed and expanded continuously in a closed cycle that is known later as Stirling
A Novel Solar Cooling system Based on a Fluid Piston Convertor
About 15% of the global electricity production is used to actuate different kinds of conventional cooling systems. Numerous solar cooling systems are commercially available but their market penetration level is relatively low due to the high capital cost and R & D activities are ongoing to reduce these costs. Operational principles of the systems for solar water pumping and dynamic water desalination were described previously which had been built around the fluid piston converter with a simple design and made of low cost materials. In water pump and desalination systems the fluid piston converter works as an engine driven by solar thermal energy accumulated by flat-plate or evacuated tube collectors. The fluid piston converter can function as a cooling machine if the fluid piston oscillations are induced by an external source. The solar cooling system which is under investigation in this research project is made of two separate parts which are coupled together. In the first part the...
Development of a Solar Cooling System Based on a Fluid Piston Convertor
2015
Solar water pumping and dynamic water desalination based on fluid piston converter were developed at Northumbria University. The fluid piston converter has a simple design and made of low cost materials. In water pump and desalination systems, the fluid piston converter works as an engine, driven by solar thermal energy absorbed by flat-plate or evacuated tube collectors. If in the same design of the converter, its fluid piston is driven using external source of energy without heat input, then such the converter works as a cooling device. In this study, the solar fluid piston engine is coupled with the cooling unit with the fluid piston of the latter driven by the fluid piston engine. This results in production of cooling effect using solar energy. The operation of such system has been investigated theoretically and experimentally. The thermodynamic model, consisting of a system of ordinary differential equations, was developed in the MATLAB/Simulink environment to simulate the operation of such the thermal auto-oscillation system. The theoretical results confirm that it is possible to achieve the temperature of the working fluid in the cycle of the cooling unit, which is below the ambient temperature. The cooling effect depends on the operational parameters of both the engine and cooling parts of the system.
Analysis of a combined power and ejector-refrigeration cycle using low temperature heat
Energy Conversion and Management, 2013
This paper presents the thermodynamic study of a thermal system which combines an organic Rankine cycle and an ejector-refrigeration cycle. The combined cycle could be driven by low-temperature heat source, that is solar energy. Required energy of combined cycle is provided by the parabolic dish collectors. According to the amount of combined cycle required energy, the number of needed collectors is calculated. For analysis of the cycle, a simulation has been performed using R123 as the working fluid. To this end, the effect of variation in heat source, the evaporator, and the cooling water temperatures as well as the expansion ratio, the input and output pressures of turbine on thermal efficiency, exergy efficiency, and exergy destruction has been investigated in each component and the entire system. Thermal efficiency and exergy efficiency of 13.41 and 24.89 % are obtained at a heat source inlet temperature of 140C. Also, it is observed that the greatest exergy destruction occurs in the steam generator.
Energy Conversion and Management, 2019
The present work investigates the implementation of low-grade solar energy in combined ejector refrigeration and an Organic Rankine cycle for cooling and power generation. In such systems, the solar radiation intensity determines the cooling path and the power produced. The proposed solar thermal system consists of two cycles, namely: the solar collector and the combined cycles. The solar thermal cycle is a parabolic trough collector, whereas the combined cycles are ejector refrigeration and an Organic Rankine cycles. The latter consists of an ejector, evaporator, condenser, expansion valve, preheater, turbine, pumps and generator. In this context, a mathematical model of the solar thermal system is established to determine and control the outlet temperature of the working fluid and the temperatures of the absorber, and the glass cover of the parabolic trough receiver. In the proposed model, the effects of the solar intensity, inclination angle and ambient conditions are included. The performance of the parabolic solar collector is evaluated depending on the meteorological data and concentrator-related parameters. The hourly-calculated results of this model for the thermal solar receiver are introduced into the simulation program of the proposed combined cycle. The fluids R601a, R123, R245fa, and R141b are used as refrigerants. In addition, the effects of the thermodynamic parameters on the system performance are investigated. The obtained numerical data are compared to experimentally obtained and published data. A good agreement is found between these data.