Modeling and Performance Optimization of an Irreversible Two-Stage Combined Thermal Brownian Heat Engine

Abstract

Based on finite time thermodynamics, an irreversible combined thermal Brownian heat engine model is established in this paper. The model consists of two thermal Brownian heat engines which are operating in tandem with thermal contact with three heat reservoirs. The rates of heat transfer are finite between the heat engine and the reservoir. Considering the heat leakage and the losses caused by kinetic energy change of particles, the formulas of steady current, power output and efficiency are derived. The power output and efficiency of combined heat engine are smaller than that of single heat engine operating between reservoirs with same temperatures. When the potential filed is free from external load, the effects of asymmetry of the potential, barrier height and heat leakage on the performance of the combined heat engine are analyzed. When the potential field is free from external load, the effects of basic design parameters on the performance of the combined heat engine are analyzed. The optimal power and efficiency are obtained by optimizing the barrier heights of two heat engines. The optimal working regions are obtained. There is optimal temperature ratio which maximize the overall power output or efficiency. When the potential filed is subjected to external load, effect of external load is analyzed. The steady current decreases versus external load; the power output and efficiency are monotonically increasing versus external load.

Power and Thermal Efficiency Optimization of an Irreversible Steady-Flow Lenoir Cycle

“…A large number of works have been performed for reciprocating (finite time) models [16][17][18][19][20][21][22][23][24][25] by applying FTT. While finite size is the major feature for steady-flow devices, such as closed gas rubine (Brayton cycle) power plants and steam (Rankine cycle) and organic Rankine cycle power plants, many scholars have performed FTT studies for various steady-flow cycles with the power output (POW), thermal efficiency (TEF), exergy efficiency, profit rate, and ecological function as the optimization goals, under the conditions of different losses and heat transfer laws .…”

Optimizing Power and Thermal Efficiency of an Irreversible Variable-Temperature Heat Reservoir Lenoir Cycle

“…As a further extension of traditional irreversible process thermodynamics, finite-time thermodynamics (FTT) [1][2][3][4][5][6][7][8][9][10][11] has been applied to analyze and optimize performances of actual thermodynamic cycles, and great progress has been made. FTT has been applied in micro-and nano-cycles [12][13][14][15], thermoelectric devices [16,17], thermionic devices [18,19], gas turbine cycles [20][21][22], internal combustion cycles [23,24], cogeneration plants [25,26], thermoradiative cell [27], chemical devices [28,29], and economics [30,31].…”

Performance Analysis and Optimization for Irreversible Combined Carnot Heat Engine Working with Ideal Quantum Gases

“…The results showed that the combined HE had three operating modes with different temperatures of WM, and the improving extents of power and efficiency linearly increased with the number of stages. For thermal Brownian engines, Qi et al [ 94 , 95 ] studied the combined thermal Brownian HE [ 94 ] and refrigerator [ 95 ] by using FTT theory. To date, the combined HE using ideal quantum gas as WM has not been studied in the open literature.…”