Search

Absorption machines are frequently used for cooling and heating. However, they must be improved to achieve high performance at a lower cost. Being a key component of these machines, this paper focuses on the absorber and specifically on falling film absorber configuration due to its compactness and simple geometry. This paper reviews the different analytical and numerical approaches used to analyze the thermal, mass and hydrodynamic phenomena occurring in falling films for both smooth and wavy-laminar regimes. It shows the significant progress made since 2000 in terms of mathematical models developed and coupling effect resolution. Research using thermodynamics to identify, locate and quantify the entropy generation sources in falling film absorbers is also presented. [ABSTRACT FROM AUTHOR]

A paper has been published in International Journal of Refrigeration, second law analysis of vapour absorption refrigeration (VAR) system using different mathematical expressions which obey thermodynamics principles. The present paper attempts to discuss and comment on the paper. Addition or subtraction of exergy of the heat flux (or exergy of heat transfer) in mathematical expression of internal irreversibility, are not meeting to direction principles of exergy flow. Therefore, internal irreversibility expressions must be corrected for future research based on second law in the field of VAR system. [ABSTRACT FROM AUTHOR]

The paper presents an investigation of the thermal performance of an innovative insulation wrap for food freezing, transportation and storage. The wrap is made of two outer polypropylene films and an internal folded polypropylene film welded together to form rectangular internal air cells. A mathematical model of heat transfer is presented and experimentally validated, with discrepancies less than 10% when there is no internal convection effect and generally less than 12% when internal convection is present. A thermal effectiveness of film usage was proposed and analyzed in order to find the best fold geometry. A mathematical model of the effectiveness and its experimental validation showed good agreement (discrepancies less than 13%). By using a criteria map, we recommend the following geometry: wrap thickness more than 5 and less than 10 mm; fold spacing more than 6 and less than 10 mm. [ABSTRACT FROM AUTHOR]