scholarly journals EFFICIENCY OF THE REGENERATIVE CYCLE OF BRIGHTON WITH VARIABLE THERMOPHYSICAL PROPERTIES OF THE WORKING FLUID (Part 2)

2018 ◽  
Vol 41 (3) ◽  
pp. 5-13
Author(s):  
A.A. Khalatov ◽  
S.D. Severin ◽  
O.S. Stupak ◽  
O.V. Shihabutinova
Keyword(s):  
Moisture Content ◽  
Thermophysical Properties ◽  
Thermal Efficiency ◽  
Second Law Of Thermodynamics ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Thermodynamic Efficiency ◽  
Carnot Cycle ◽  
Regenerative Cycle ◽  
The Ideal

The data about thermodynamic efficiency of the ideal Brighton cycle with heat regeneration with constant thermophysical properties of the working fluid, as well as the Brighton cycle with heat recovery and the wetting of the working fluid at the inlet to the turbine (with variable thermophysical properties of the working fluid). The inapplicability of comparison of the thermal efficiency of the Brighton cycle with heat recovery and the wetting of the working fluid at the inlet to the turbine with the thermal efficiency of the equivalent ideal Carnot cycle is shown. The analysis of the thermodynamic efficiency of an ideal regenerative Brighton cycle with a decrease in the working body at the entrance to the turbine allows us to make the following conclusions: With the growth of the mass moisture content of the working fluid when entering the turbine, the thermal efficiency of the regenerative cycle increases, but decreases with an increase in the degree of increase in the pressure level in the cycle. High values ​​of the thermal efficiency of the cycle () can be achieved with relatively small values ​​of the degree of increase in the pressure in the cycle () and high (up to d = 0,5) values ​​of the mass moisture content of the working body when entering the turbine. It is shown that under certain conditions the thermal efficiency of the regenerative cycle with the decrease of the working body when entering the turbine may be greater than the thermal efficiency of a similar ideal Carnot cycle, which does not contradict the second law of thermodynamics, since the condition for the implementation of the Carnot cycle is the immutability of the thermophysical properties of the working body in a loop In this regard, the use of the expression for the thermal efficiency of the ideal Carnot cycle is not used as a criterion for assessing the efficiency of cycles of power plants with highly variable thermophysical properties of the working fluid. It is also shown that the thermal efficiency of the regenerative cycle with the decrease of the working body when entering the turbine is always lower than the thermal efficiency of the equivalent non-equilibrium Carnot cycle with a change in the specific heat of the working fluid, which corresponds to the second law of thermodynamics. It is shown that the Brighton regenerative cycle with a decrease in the working body before the turbine can be represented as a conditional cycle with a higher maximum temperature of the cycle, which, depending on the mass content of the moisture content of the working body, can in 1,2 ... 2,5 times exceed the actual maximum temperature cycle, which determines the high values ​​of its thermal efficiency.

scholarly journals Efficiency of the regenerative cycle of Brighton with variable thermophysical properties of the working fluid

2019 ◽  
Vol 41 (2) ◽  
pp. 5-10
Author(s):  
A.A. Khalatov ◽  
S.D. Severin ◽  
O.S. Stupak
Keyword(s):  
Thermophysical Properties ◽  
Thermal Efficiency ◽  
Heat Recovery ◽  
Nuclear Power ◽  
Power Plants ◽  
Fourth Generation ◽  
Working Fluid ◽  
Thermodynamic Efficiency ◽  
Carnot Cycle ◽  
Heat Regeneration

The desire to increase the thermodynamic efficiency of power machines and units now leads to use of gas turbine units with heat recovery in the cycle. Such devices are used as power and transport GTUs, as well as energy conversion units for prospective fourth generation nuclear power plants. Thermodynamic efficiency of the ideal Brighton cycle with heat regeneration with constant thermophysical properties of the working fluid, as well as the Brighton cycle with heat recovery and the wetting of the working fluid at the inlet to the turbine (with variable thermophysical properties of the working fluid) is considered in this paper. The inapplicability of comparison of the thermal efficiency of the Brighton cycle with heat recovery and the wetting of the working fluid at the inlet to the turbine with the thermal efficiency of the equivalent ideal Carnot cycle is shown.

scholarly journals Thermal efficiency of the regenerative cycle of the Stirling engine scheme gamma

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
N. M. Sharpar ◽  
◽  
L. I. Zhmakin ◽  
Keyword(s):  
Energy Efficiency ◽  
Thermal Inertia ◽  
Stirling Engine ◽  
Working Fluid ◽  
Carnot Cycle ◽  
Energy Costs ◽  
Working Process ◽  
Hot Gas ◽  
Cold Area ◽  
Regenerative Cycle

The paper presents a theoretical model of the Stirling engine-gamma scheme, based on thermodynamic dependencies describing the working process taking into account the efficiency of the regenerator. The measurement of the gas pressure in the cycle, due to which its operation was carried out, is carried out by means of a plunger moving along the cylinder. Cooling in the working cylinder circuit is carried out at the expense of the environment. Due to the movement of the working fluid between the cylinders, there is an increase or decrease in pressure, which requires energy costs that affect the operation of the engine. An increase in the energy efficiency of the Stirling engine is achieved by introducing a regenerator into it, which helps to minimize heat losses. This device is located between the hot and cold cylinder, it is a cavity that contains a porous material that receives heat flowing with hot gas into the cold area, when it is moved back before entering the heater, the regenerator returns the stored heat. Due to the introduction of the regenerator in the model, the engine increases energy efficiency, and the efficiency of its cycle reaches the efficiency of the Carnot cycle. In this paper, the authors apply thermodynamic laws to represent the processes that underlie the functioning of the Stirling machine, not only in its cylinders, but also in the battery, the analysis of thermal inertia of which confirms the above study.

The Effect of Material Properties on the Thermal Efficiency of the Minto Solar Wheel

1980 ◽  
Vol 102 (2) ◽  
pp. 504-507 ◽  
Author(s):  
S. Lin ◽  
R. Bhardwaj
Keyword(s):  
Thermal Performance ◽  
Thermal Efficiency ◽  
Material Properties ◽  
Working Fluid ◽  
Working Fluids ◽  
Mean Diameter ◽  
The Mean ◽  
The Ideal

The characteristic of the thermal performance of the Minto solar wheel is that its thermal efficiency is strongly dependent on the material properties of the working fluid. For a specified working fluid, the thermal efficiency of the ideal cycle of the Minto solar wheel is dependent only on the mean diameter of the wheel. To study the effect of the material properties of the working fluid on the ideal thermal efficiency, 14 working fluids are selected, and their thermal efficiencies as functions of the mean diameter of the wheel are calculated and compared with each other. Among these fluids, R-12, R-115, R-500, R-22 and R-13B1 achieve better thermal performance than the others.

The Basic Thermodynamics of Turbine Cooling

2000 ◽  
Vol 123 (3) ◽  
pp. 583-592 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Combustion Temperature ◽  
Plant Performance ◽  
Maximum Temperature ◽  
Working Fluid ◽  
Turbine Plant ◽  
Cooling Flows ◽  
Turbine Cooling ◽  
Gas Turbine Plant

Analyses of gas turbine plant performance, including the effects of turbine cooling, are presented. The thermal efficiencies are determined theoretically, assuming air standard (a/s) cycles, and the reductions in efficiency due to cooling are established; it is shown that these are small, unless large cooling flows are required. The theoretical estimates of efficiency reduction are compared with calculations, assuming that real gases form the working fluid in the gas turbine cycles. It is shown from a/s analysis that there are diminishing returns on efficiency as combustion temperature is increased; for real gases there appears to be a limit on this maximum temperature for maximum thermal efficiency.

Performance Comparison of Gas Turbine Cycle Combined With Supercritical CO2 Recompression and Regenerative Cycle

2018 ◽  
Author(s):  
Yuqi Han ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Haoxiang Chen
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Supercritical Co2 ◽  
Performance Comparison ◽  
Maximum Temperature ◽  
Micro Gas Turbine ◽  
Coupling Methods ◽  
Gas Turbine Cycle ◽  
Recompression Cycle ◽  
Regenerative Cycle

With the aim to recover waste heat from a specific micro gas turbine (MGT), and improve the thermal efficiency and the system compactness, simulation models of regenerative gas turbine cycle combined with supercritical CO2 recompression cycle and supercritical CO2 regenerative cycle respectively are developed. The influence of the introduction of the gas turbine recuperator with three cycle coupling methods on the thermal efficiency of the system is discussed. Compare to the micro gas turbine system combined with supercritical CO2 regenerative cycle, the improved system can increase the thermal efficiency and the output power by 3.32 percent point and 10.54% respectively. The impact on system performance of cycle parameters, including split ratio, the maximum temperature of the bottoming cycle, the recuperator effectiveness of the bottoming cycle and the hot side outlet temperature of the intermediate heat exchanger have been analyzed and optimized. From the viewpoints of the thermal efficiency and the heat transfer area, performance comparison between two bottoming cycles with different coupling methods is done. The multi-objective optimization study shows that the regenerative gas turbine cycle coupled in series with supercritical CO2 recompression cycle performs better than that coupled in parallel with supercritical CO2 regenerative cycle in terms of thermal efficiency.

scholarly journals Analysis of a thermal cycle that surpass Carnot efficiency undergoing closed polytropic transformations

2019 ◽  
Vol 15 ◽  
pp. 6165-6182
Author(s):  
Ramon Ferreiro Garcia ◽  
Dr. Jose Carbia Carril
Keyword(s):  
Thermal Efficiency ◽  
Thermal Cycle ◽  
Research Work ◽  
Mechanical Work ◽  
Working Fluid ◽  
Specific Work ◽  
Adiabatic Expansion ◽  
Thermal Cycles ◽  
Active Processes ◽  
The Ideal

This research work deals with a feasible non-regenerative thermal cycle, composed by two pairs of closed polytropic-isochoric transformations implemented by means of a double acting reciprocating cylinder which differs basically from the conventional Carnot based thermal cycles in that: -it consists of a non condensing mode thermal cycle -all cycle involves only closed transformations, instead of the conventional open processes of the Carnot based thermal cycles, -in the active processes (polytropic path functions), as heat is being absorbed, mechanical work is simultaneously performed, avoiding the conventional quasi-adiabatic expansion or compression processes inherent to the Carnot based cycles and, -during the closed polytropic processes, mechanical work is also performed by means of the working fluid contraction due to heat releasing. An analysis of the proposed cycle is carried out for helium as working fluid and results are compared with those of a Carnot engine operating under the same ratio of temperatures. As a result of the cycle analysis, it follows that the ratio of top to the bottom cycle temperatures has very low dependence on the ideal thermal efficiency, but the specific work, and, furthermore, within the range of relative low operating temperatures, high thermal efficiency is achieved, surpassing the Carnot factor.

Energy saving and climate change mitigation through improved thermodynamic efficiency

2020 ◽  
Vol 33 (3) ◽  
pp. 283-288
Author(s):  
Emilio Panarella
Keyword(s):  
Climate Change ◽  
Energy Saving ◽  
Climate Change Mitigation ◽  
Second Law Of Thermodynamics ◽  
Thermodynamic Cycle ◽  
Thermodynamic Efficiency ◽  
Carnot Cycle ◽  
Thermodynamic Cycles ◽  
The Subject ◽  
Change Mitigation

The second Law of Thermodynamics is fundamental in the analysis of thermodynamic cycles. It dictates that the conversion of heat to work is limited. It reaches an upper limit in a classical thermodynamic cycle, and such a limit is provided by the Carnot cycle, which is the most efficient. Motivated by a recent allowance of a patent to this author (U.S. Patent 10,079,075), the present study tutorially attempts to expand on the subject and shows that the efficiency can go above the Carnot efficiency, provided a novel cycle is used, and heat, rather than being discarded, is recirculated in the same engine used to generate work. The significant energy saving consequential to this finding and climate change mitigation are reported.

scholarly journals Quantum Lenoir Engine with a Single Particle System in a One Dimensional Infinite Potential Well

POSITRON ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 81
Author(s):  
Yohanes Dwi Saputra
Keyword(s):  
Quantum System ◽  
Single Particle ◽  
Thermal Efficiency ◽  
Particle System ◽  
Ideal Gas ◽  
Working Fluid ◽  
Potential Well ◽  
One Dimensional ◽  
Infinite Potential Well ◽  
The Ideal

Lenoir engine based on the quantum system has been studied theoretically to increase the thermal efficiency of the ideal gas. The quantum system used is a single particle (as a working fluid instead of gas in a piston tube) in a one-dimensional infinite potential well with a wall that is free to move. The analogy of the appropriate variables between classical and quantum systems makes the three processes for the classical Lenoir engine applicable to the quantum system. The thermal efficiency of the quantum Lenoir engine is found to have the same formulation as the classical one. The higher heat capacity ratio in the quantum system increases the thermal efficiency of the quantum Lenoir engine by 56.29% over the classical version at the same compression ratio of 4.41.

scholarly journals On the Assumption of the Independence of Thermodynamic Properties on the Gravitational Field

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 930
Author(s):  
Corti
Keyword(s):  
Gravitational Field ◽  
Thermodynamic Properties ◽  
Internal Energy ◽  
Center Of Mass ◽  
Second Law Of Thermodynamics ◽  
Ideal Gas ◽  
Thermodynamic Efficiency ◽  
Second Law ◽  
Cyclic Process ◽  
Carnot Cycle

A reversible cyclic process is analyzed in which the center of mass of an ideal gas is raised in a gravitational field during both an expansion phase and a subsequent contraction phase, with the gas returning to its initial height in a final step. When the properties of the gas are taken as uniform, the thermodynamic efficiency of this cycle is able to exceed that of a corresponding Carnot cycle, which is a violation of the second law of thermodynamics. The source of this discrepancy was previously claimed, when analyzing a similar heating and cooling of a sphere, to be the assumed independence of the internal energy on the gravitational field. However, this violation is only apparent since all of the effects of the gravitational field were not incorporated fully into the thermodynamic analysis of the cycle. When all the influences of the gravitational field are considered, no possible violation of the second law can occur. The evaluation of the entropy changes of the gas throughout the cycle also highlights other key inconsistencies that arise when the full effects of the gravitational field are neglected. As the analysis of the cycle provided here shows, the assumption of the independence of the internal energy, as well as other thermodynamic properties, on the gravitational field strength can still be invoked.

Investigation on Operating Processes for a New Solar Cooling Cogeneration Plant

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
R. Shankar ◽  
T. Srinivas
Keyword(s):  
Power Generation ◽  
Thermal Efficiency ◽  
Power Efficiency ◽  
Climatic Conditions ◽  
Coefficient Of Performance ◽  
Maximum Temperature ◽  
Specific Power ◽  
Working Fluid ◽  
Water Mixture ◽  
Cogeneration Plant

Some commercial units and industries need more amount of cooling than the power such as cold storage, shopping complex, etc. In this work, a new cooling cogeneration cycle (Srinivas cycle) has been proposed and solved to generate more cooling with adequate power generation from single source of heat at hot climatic conditions with ammonia–water mixture as a working fluid. The operational processes conditions for the proposed cooling cogeneration plant are different compared to the power-only (Kalina cycle system) system and cooling-only (vapor absorption refrigeration) system. This work focused to generate the optimum working conditions by parametric analysis from thermodynamic point of view. An increase in cycle maximum temperature is only supporting the power generation but not the cooling output. Cooling output is also 15 times more than power generation. So, it has been recommended to operate the integrated plant with low temperature heat recovery. The resulted cycle thermal efficiency, plant thermal efficiency, specific power, specific cooling, cycle power efficiency, cycle coefficient of performance (COP), and solar collector's specific area are 27%, 10%, 15 kW, 220 kW, 1.8%, 0.25, and 10 m2/kW, respectively.

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