Study On The Electrode Reaction And Basic Cycle Of The Thermally Regenerative Ammonia Battery

The thermally regenerative ammonia battery(TRAB)is a new type of electrochemical battery,which utilizes low-grade thermal heat to produce electricity and has the advantages of simple structure,recyclable regeneration and environmental friendly characteristic.Up to now,the studies of TRAB mainly focused on the ion exchange membrane material,the structure improvement,the development of new application and so on,while researches on the thermophysical mechanisms of electrode reaction and regenerative cycle are relatively few.Therefore the following work was carried out in this thesis:(1)Experiments were done to measure the electrode potential of TRAB in a wide range of electrolyte concentration and temperature.At atmospheric pressure,the positive and negative electrode potentials of TRAB using(0.1?.5)mol/L nitrate solution as electrolyte in the range of(20?50)? were measured.The temperature coefficients of electrode potential were obtained by fitting,being(-0.955--0.806)mV/K and(-0.523?-0.390)mV/K respectively for the anode and the cathode.A test device was established for experiments above normal pressure.Thereafter the negative electrode potentials of TRAB using(4.0?5.0)mol/L nitrate solution as electrolyte in the range of(30?50)? were measured,and the temperature coefficient was fitted to be(-1.100?-0.928)mV/K.(2)Theoretical analysis of TRAB electrode reaction was carried out.An electrode model of chemical reaction equilibrium and electrolyte solution activity was established,and the electrode potentials were estimated using parameters from the reference.For the temperature coefficients of positive and negative electrode potential,the deviations between the estimated values of and the experimental values were 5.38%and 10.07%respectively.For the negative electrode potential the relative deviation was 7.81%.After fitting the interaction parameter BCu(NH3)42+.NO3-of the activity model with the experimental data,the relative deviation of the negative electrode potential could be reduced to 2.97%.Thermodynamic analysis of TRAB showed that theoretical electrical work and reversible thermal effect increase with the battery working temperature in the range of(20?50)?,while the discharge efficiency decreases with the battery working temperature.(3)A basic cycle of TRAB was simulated with Aspen HYSYS software and the effects of several factors on cycle performance were studied.The battery working temperature was fixed at 30 ? and the working pressure was fixed at 101.3 kPa.It was found that optimum feeding position exists,which makes the cycle thermal efficiency maximized.The effect of regenerative temperature is very significant,when it increases from 75 ? to 100 ?,the thermal efficiency changes from 0.99%to 3.36%,and the thermodynamic perfect degree increases from 0.0528 to 0.2601.In the range of(20?45)?,the condensing temperature has minor effect on the thermal efficiency and thermodynamic perfection.