The Performance Characteristics Of Two Type Particle-exchange Heat Engine And Refrigerator

The working substance is all kinds of classical matter in traditional heat engines and refrigerators.In recent years with the development of the theoretical research and the need of practice,a new type heat engine and refrigerator whose working substance is electrons is proposed,i.e.electronic engine.The electronic engine consists of two infinitely large electron reservoirs,which have different temperatures and chemical potentials.Under the temperature gradients and chemical potentials,electrons can transport in special direction.According to the first law of thermodynamics,a amount of heat can be absorbed from and released to two different electron reservoirs with transportation of electron.So a amount of heat flux appear corresponding to a amount of electron flux between two electron reservoirs.Moreover,T.E.Humphrey,H.Linke,et al try to select electrons to transport by using a single "idealized energy filter".It is energy selective electron(ESE) heat engine and refrigerator which we study in the thesis.But the ESE heat engine and refrigerator proposed by T.E.Humphrey,et al are very idealized theoretical models.Actually,due to temperature difference and the different property between two electron reservoirs,some non-ideal factors of the models exist, such as heat conduction and heat radiation.So,it is necessary to analyze the performance characteristics of the ESE heat engine and refrigerator with radiative heat leaks considering above these factors.The performance characteristics of the ESE heat engine and refrigerator with radiative heat leaks are studied in the chapterâ…¡and chapterâ…¢.The influence of energy position of the filter,the width of the filter and the coefficient of radiative heat leaks on performance of the system is analyzed.The performance characteristics of the ESE refrigerator with double resonant filters are studied in the chapterâ…£.The influence of energy position of double filters,the width of the filter and the energy space of two filters on performance of the system is discussed.The results obtained here are more detailed and general than these original results.And the results provide a more advanced theoretical guidance for the design of practical electronic heat engine and refrigerator.According to the theory of thermionic emission and Richardson's equation,in early year,V.C.Wilson and J.M.Houston studied the conversion of heat to electricity or electricity to heat by thermionic emission,and analyzed the efficiency of the thermionic energy converter devices.Later,thermionic emission in heterostructures was proposed by A.Shakouri and J.E.Bowers.By the foundation,thermionic refrigerator based on thermionic emission in heterostructures was proposed by G.D.Mahan,L.M.Woods,et al.Now,the vacuum thermionic refrigerator based on thermionic emission is studied in chapterâ…¤,importantly,the influence of external magnetic field on performances of the model is firstly discussed here.Some optimal performance of vacuum thermionic refrigerator under external magnetic field are obtained by numerical calculation.Based on the theory of chapterâ…¤,vacuum thermionic heat engine under external magnetic field is firstly proposed in chapterâ…¥,then the performance characteristics of the model are studied,and some optimal performances are obtained by numerical calculation.The analysis of performance characteristics of the models give some theoretical guidance for obtaining optimal work performance by controling external field.In the thesis,the performance characteristics of two type particles-exchange heat engine and refrigerator are studied.By theoretical analysis and numerical calculation,the work is presented by the following chapters:In chapterâ…¡,based on selection of a single energy filter to electrons transportation, in the electron heat engine system which consists of two different electron reservoirs the density of net electron flow is calculated as the distribution function of energy in different electron reservoirs by using Fermi-Dirac statistical distribution,and the corresponding heat flow expressions is obtained.Next,the several performance parameters of a single energy filter ESE heat engine with heat radiation are derived.The influence of the coefficient of radiative heat leak and energy filter between two reservoirs on performance of the ESE heat engine is analyzed.The performance characteristic curves of the system are plotted by numerical analysis,so the methods for improving performance of the system are obtained.The ESE system behaves as a heat engine when the E_r＞E₀ in the chapterâ…¡. Now,the same ESE system behaves as a refrigerator when the E_r＜E₀ in the chapterâ…¢.Based on the theory of the chapterâ…¡,the performance characteristics of the single energy filter ESE refrigerator with heat radiation are analysed.In chapterâ…£,based on selection of double energy filters to electrons transportation, in the electron refrigerator system which consists of two different electron reservoirs the density of net electron flow is calculated as the distribution function of energy in different electron reservoirs by using Fermi-Dirac statistical distribution,and the corresponding heat flow expressions are obtained in two energy filters.Next,the several performance parameters of ESE refrigerator with double energy filters are derived.The influence of energy position of the energy filter,the width of the energy filter and the energy space of two filters on performance of the ESE refrigerator is analyzed.The performance characteristic curves are plotted by numerical analysis,and then the methods for improving performance of the system are obtained.In chapterâ…¤,based on the dynamics equation of electron motion in magnetic field and Richardson's equation,the vacuum thermionic refrigerator under external magnetic field is established.According to Richardson's equation in statistical physics,the expressions of the density of electron flow between two electrodes are derived.Moreover, according to the heat effect of electron transportation,the expressions of the cooling power and coefficient of performance of vacuum thermionic refrigerator under external magnetic field are dirived.The performance characteristics of the model are analysed by numerical calculation.The analysis of performance characteristics of the model gives some theoretical guidance for obtaining optimal work performance by controling external field.Based on the theory and model of the chapterâ…¤,the direction of the net electrons flow is reversed by changing the applied voltage,i.e.the vacuum thermionic heat engine appears in the chapterâ…¥.Similarly,the expressions of the power output and efficiency of the vacuum thermionic heat engine under external magnetic field can be derived.The performance characteristics of the model are analysed by numerical method.