Experimental Study of the Thermal Effect of the Dissolution Reaction for Some Alkalis and Salts with Natural Mixing and Forced Stirring

Abstract

The paper presents the results of an experimental study of the exothermal and endothermal effects occurring on the dissolution of potassium nitrate KNO3, ammonium nitrate NH4NO3, potassium hydroxide KOH and sodium hydroxide NaOH, in distilled water with natural mixing and forced stirring. It is shown that for natural mixing, NH4NO3 and KOH are the most appropriate working substances for cooling and heat generation respectively, while for forced stirring, NH4NO3 and NaOH display better performance. The optimal concentrations of the liquid solutions for achieving extreme temperatures and maximal enthalpy changes are also defined. In addition, the regression function and regression coefficients describing correlations between the total enthalpy change of the calorimetric system and the solution concentration are found, for the most suitable liquid solutions. The experimental results obtained can be used to develop generating reactors for exothermal heating and endothermal cooling for a thermochemical seasonal storage system able to store solar heat or heat from combined heat and power (CHP) units of biogas plants in summer, for heating purposes in winter, while generating cooling to support air conditioning systems in summer.