Thermodynamic Performance Study Of Three-terminal Thermoelectric Devices Based On Coupled Quantum Dots

In this thesis,the thermodynamic performance characteristics and optimal analysis of a hybrid driven three-terminal thermoelectric refrigerator based on two coupled quantum dots,a four-terminal thermoelectric heat engine and refrigerator based on three coupled quantum dots are studied.We derive the analytic expressions for thermodynamic performance parameters of these thermoelectric systems,and then optimize the these parameters reasonably to improve the thermodynamic performance of thermoelectric devices in the steady-state case.The main contents of this thesis are as follows:In chapter 1,we mainly introduce the thermoelectric devices’ research background and the different thermoelectric materials and structures’ influence on the thermoelectric devices’ performance,explain the main methods and theories for our research,and analyze the thermoelectric devices’ general working principle.In chapter 2,we propose a new model of a hybrid driven three-terminal thermoelectric refrigerator based on two capacitively coupled quantum dots.The model consists of two capacitively coupled quantum dots,where one of the quantum dots is coupled with an electron reservoir at the highest temperature and an electron reservoir at the intermediate temperature respectively and there is a chemical potential difference between the two reservoirs,another quantum dot is coupled with a single cold reservoir.Based on master equation and basic thermodynamic formulas we derive the charge and energy currents’ expressions between two quantum dots and the corresponding thermal reservoirs and analyze the direction of these currents.Then,we define the cooling rate and coefficient of performance as a hybrid driven refrigerator,and get the corresponding working regions.The refrigerator’s performance characteristic graphs are plotted by numerical simulation,and some new conclusions are obtained by analyzing the these graphs.Lastly,the refrigerator’s performance parameters are optimized in order to get the maximum cooling rate.In chapter 3,we propose a four-terminal heat engine model based on three capacitively coupled quantum dots.This model consists of three capacitively coupled quantum dots,where one of the quantum dots is coupled with two cold electron reservoir,while the other two quantum dots are coupled with a hot reservoir and a intermediate temperature reservoir,respectively.Based on master equation and basic thermodynamic formulas we derive the expressions for the charge and energy currents between three quantum dots and thermal reservoirs in weak/strong capacitive coupling case,and define the power output and efficiency.By numerical simulation we plot the device’s performance characteristic graphs.Then,in order to get the maximum output power we optimize the performance parameters.Lastly,we compare the performance characteristics of the heat engine in strong and weak capacitive coupling cases.In chapter 4,on the basis of the four-terminal thermal heat engine with three capacitively coupled quantum dots,we propose a new four-terminal thermoelectric refrigerator model with three capacitively coupled quantum dots,which can refrigerate the coldest reservoir by investing thermal power and electric power.We analyze the working principle and plot the refrigerator’s performance characteristics by numerical simulation.Lastly,we optimize the performance parameters of the hybrid driven thermoelectric refrigerator.In chapter 5,we summarize the main work of this thesis.