Study On The Performance Of Quantum Thermal Devices Driven By Non-equilibrium Thermal Bath

The intersection of quantum mechanics and classical thermodynamics gives rise to the new quantum thermodynamics.In this field,the study of quantum heat engine is one of the main contents of quantum thermodynamics.Quantum heat engine provides an effective way and method for people to reveal the physical nature of macroscopic thermodynamic phenomena from the micro-point of view.It is an important means and tool for people to explore the thermodynamic characteristics of quantum system.At present,the research on the performance of quantum heat engines not only involves different types of cycle models,such as Carnot cycle,Otto cycle,Brayton cycle,Diesel cycle,Ericsson cycle,Stirling cycle,etc.,but also considers the influence of different working substances on the performance of heat engines,such as resonance subsystem,spin 1/2 system,etc.The effects of different thermal baths on the performance of heat engines,such as squeezing and coherence of thermal baths,are also studied.In this paper,the performance of quantum thermal devices driven by non-equilibrium thermal bath(squeezed thermal baths)is studied.In this paper,an endoreversible quantum Carnot heat engine and refrigerator cycle model with harmonic systems and spin 1/2 system as working substance is established.The expressions of physical quantities such as heat,work,time,power,figure of merit and effective inverse temperature of thermal bath related to squeezing parameters are derived.Through the optimization calculation respect to inverse high and low-temperature of working substance,the analytical expressions of the efficiency for the endoreversible quantum Carnot engine and the performance coefficient of the endoreversible quantum refrigerator for two different working substances are obtained.The essence and connotation of the influence of the squeezing degree of the thermal bath on the cycle performance of the endoreversible quantum Carnot engine and the refrigerator are revealed.The paper study the effect of Mpemba effect on the performance of Otto refrigerator,and the results show that the Markov-Mpemba effect can significantly improve the performance of Otto refrigerator without reducing its stability for a given coefficient of performance.In this paper,a quantum endoreversible Carnot engine cycle and its inverse operation-Carnot refrigeration cycle with harmonic systems as working substance,working between a hot bath of inverse temperature βh and a cold bath at inverse temperatureβc has been considered.For the engine model,the hot bath is constructed to be squeezed,whereas for the refrigeration cycle,the cold bath is set to be squeezed.In the high-temperature limit,the efficiency at maximum power and coefficient of performance at maximum figure of merit has been analyzed,revealing the effects of the times allocated to two thermal-contact and two adiabatic processes on the machine performance.The study show that,when the total time spent along the two adiabatic processes is negligible,the efficiency at maximum power reaches its upper bound,which can be analytically expressed in terms of squeezing parameter r:η*ana=ηCAgen=1-(?),with the Carnot efficiency ηC=1-βh/βc and the coefficient of performance at maximum figure of merit is bounded from the upper side by the analytical function:ε*ana=εCAgen=(?),whereεC=βh/(βc-βh),the results follow the second law of thermodynamics.The results show that the performance of reversible Carnot engine cycle and Carnot refrigerator cycle based on harmonic systems can be greatly improved by squeezing of thermal bath.The finite-time performance of a quantum endoreversible Carnot engine cycle and Carnot refrigeration cycle,employing a spin-1/2 system as the working substance has been investigated.The thermal machine is alternatively driven by a hot boson bath of inverse temperature βh and a cold boson bath at inverse temperature βc(>βh).While for the engine model the hot bath is constructed to be squeezed,in the refrigeration cycle the cold bath is established to be squeezed with squeezing parameter r.The analytical expressions for both efficiency and power in heat engines and for coefficient of performance and cooling rate in refrigerators have been obtained.The study find that,in the high-temperature limit,the efficiency at maximum power is bounded by the analytical value η+=1(?),and the coefficient of performance at the maximum figure of merit is limited by ε+=(?),where ηC=1-βh/βc andεC=βh/(βc-βh)are the respective Carnot values of the engines and refrigerators.These analytical results are identical to those obtained from the Carnot engines based on harmonic systems,indicating that the efficiency at maximum power and coefficient at maximum figure of merit are independent of the working substance.The results also follow the second law of thermodynamics.It is shown that the performance of the quantum endoreversible Carnot and refrigerator cycles working on the spin 1/2 system is obviously improved by the squeezing of the thermal bath.In this paper,the effect of Mpemba effect on the performance of Otto refrigerator has been studied.For whether Mpemba effect exists or not,when the condition of Mpemba effect is satisfied and the system is in periodic steady state,by considering the distance balance function(Kuhlbeck-Lebler divergence),the time expression in the process of heating and cooling relaxation,and measure the physical quantities of the system such as heat,work and cooling rate have been determined.For the two different versions of the system,the heat absorption from low-temperature thermal bath,cooling rate,figure of merit and fluctuation have been numerically evaluated and compared.The results show that the Markov-Mpemba effect can significantly improve the performance of Otto refrigerator without reducing its stability for a given coefficient of performance.The conclusions of this paper have important academic significance and reference value in the performance research and optimization of the cycle model of quantum heat engine and refrigerator.