Evaluation of the effects of water agitation by air injection and water recirculation on the heat transfer coefficients in immersion cooling

Abstract

a b s t r a c tMost industrial food cooling is performed by air blast, water spraying and immersion cooling. Immersion cooling is simple, with low operational cost and leads to food quick cooling. The objective of this work was to investigate the influence of water agitation method (water injection, air injection and water injection coupled to a Venturi ejector) on the average heat transfer coefficient (h) between food and cooling water. Time-temperature evolutions of a sphere immersed in the cooling media were used to determine the heat transfer coefficients at different positions in a cooling tank. Air injection and water injection coupled with a Venturi ejector significantly increased the heat transfer coefficient between food and cooling water. For the investigated conditions, h was increased up to eight times, when air injection was used. However, the complex flow of bubbles and water inside the tank created heterogeneous water agitation, creating zones with different heat transfer coefficients. Furthermore, the use of water recirculation coupled with a Venturi ejector can be very convenient for cases where pressurized air is not available, but the best agitation solution depends on each case.

Comportamento De Variáveis Críticas Na Etapa De Resfriamento De Uma Linha De Processamento De Abate De Frangos

“…Para o pré-resfriamento de carcaças de frango, o método por imersão em tanques contínuos com água gelada é o mais comum, sendo o mais adotado pelos frigoríficos brasileiros (LAURINDO et al, 2010). É realizado em resfriadores lineares contínuos, tipo rosca sem fim, denominados chillers.…”

Experimental Approach to Assess Evaporative Cooling Under Forced Air Flow

“…Processing time and weight loss are important parameters regarding the design of chilling lines for the quality of many food products. Conventional methods such as slow air, air blast, water immersion, and water spraying have been widely used in in-dustrial chilling of food products (Dincer, 1997a;Sun and Wang, 2004;Laurindo et al, 2010a;Laurindo et al, 2010b), each one with its own advantages and disadvantages. Alternatively, rapid chilling methods increase food safety, improve quality, prevent microbial growth, and might reduce evaporative weight losses (Erdogdu et al, 2005).…”

“…It is well known that water chilling is a very efficient procedure for food cooling due to the high heat transfer coefficients between the product and chilling water (Laurindo et al, 2010b). Some products such as peas, radishes, cantaloupes, peaches, cherries, oranges, shrimps, crabs, sardines, tuna, and poultry carcasses are usually cooled by water immersion (Dincer, 1997b;Lucas and Raoult-Wack, 1998;Teruel et al, 2003;Amendola and Teruel, 2005).…”

Evaluation of convective heat transfer coefficient between fluids and particles in suspension as food model systems for natural convection using two methodologies

“…Including, heat exchange for non-Newtonian fluids and irregular particles (Alhamdan and Sastry, 1990), nonNewtonian fluids and regular items (Awuah et al, 1993Baptista et al, 1997;Palazoglu, 2006); heating/cooling of food particles in Newtonian fluids (Dincer, 1997;Hulbert et al, 1997;Carson et al, 2006;Laurindo et al, 2010); frying processes of food items (Costa et al, 1999;Sahin et al, 1999;Budzaki and Seruga, 2005;Seruga and Budzaki, 2005), aseptic processing in continuous flow (Ramaswamy and Zareifard, 2000;Chakrabandhu and Singh, 2002;Palazoglu and Sandeep, 2002), industrial freezing (Amarante and Lanoisellé, 2005), and during end-over-end agitation of canned food items (Anantheswaran and Rao, 1985;Sablani and Ramaswamy, 1998;Varga and Oliveira, 2000;Meng and Ramaswamy, 2007;Dwevedy and Ramaswamy, 2009), among others. Additional information on heat transfer between fluid and particulate foods is required, in which its quantification has remained as a challenging issue of the transport phenomena in food engineering.…”