Design of exchangers based on heat pipes for hot exhaust thermal flux, with the capability of thermal shocks absorption and low level energy recovery

This work analyzes the mathematical model of thermal exchange in presence of transitory subjected to unexpected thermal shocks of indefinite duration. It has been considered an heat pipes based liquid to air heat exchanger. This specific application can be useful in many automotive applications. This paper suggests two important applications: absorption and recovery of thermal variation and anomalies both in the refrigerant and in the exhausts, with the possibility of thermal energy recovery. This low cost recovered thermal energy could be dedicated to any necessary application.A significant scientific production was produced during the last decades and many cases have been rigorously resolved single in particular conditions. The greater part of scientific publications analyzes the transient models of common heat exchangers (Spiga, Mishra and others) or pressurized long ducts with variations in terms of pressure (Thorley and Tiley).The proposed numerical solution of the exchanger is obtained under precise simplified hypotheses based on the physical model: all the physical property of the hot fluid and of the cooling fluid are dependent on the time; external walls have a negligible thermal exchange if compared with the body of the exchanger and could be considered adiabatic; the circumferential conduction negligible if is confronted to the radial conduction; heat pipes can be considered like simple conductors with a low thermal inertiaThe solutions of the equations which describe the problem are obtained in a general and non dimensional form. They could so be easily extended to whichever exchanger, on the base of the common, verified and validated, calculation parameters which could be found in bibliography.A Matlab code to solve the problem is produced and validated thought CFD simulations. In the present paper it has been presented a complex study realized both using theoretical analysis of the situation and CFD simulation, using the Ansys Fluent code, which permit to analyze and verify the results. At the moment no experimental facility but the authors decided to publish these preliminary results in order to evaluate the possibility of international cooperation.