Experimental and theoretical study of an open multi-compartment absorption heat transformer for different steam temperatures. Part I: hydrodynamic and heat transfer characteristics

Abstract A novel multi-compartment absorption heat transformer for different steam temperatures (MAD) has been developed. The MAD-transformer was designed to cope with the common situation prevailing in many process industries where there is both a need for different steam temperatures and access to waste vapour at various temperatures. Both the absorber and generator are partitioned in a number of compartments which depend on the number of high quality steam demands and waste vapour sources, respectively. The circulation of the working medium is quite low which causes a fairly high concentration change and thereby different temperatures in the compartments. The low circulation ratio eliminates the need for heat exchange between the generator and the absorber. A pilot-plant unit consisting of an absorber and a steam generator was designed and installed. The absorber consists of four compartments confined between five vertical lamellas. A number of experiments were performed, to investigate the hydrodynamic and heat transfer characteristics of the multi-compartment absorber using three different working fluid pairs. The distance between lamellas, apparent refrigerant level inside a lamella, flow rate of inlet steam to the compartments, flow rate of refrigerant to the lamellas, solution viscosity, and boiling point elevation of the absorbent are the process variables investigated. In Part I of this work, the working principles, control strategies, hydrodynamic behavior as well as the heat transfer characteristics of this MAD-transformer are reported.