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Agricultural biotechnology and food biotechnology
Development of a Heat and Mass Transfer Model to Simulate the Conventional Chilling of a Beef Carcass
Ross Gilsenan1, Niall O’Murchú1, Graham Fahey1, Joe Hannon1,3, Garrett Keane2
1School of Mechanical Engineering and Design, DIT
2School of Civil Engineering, DIT
3School of Biosystems Engineering, UCD
A coupled heat and mass transfer model was developed to simulate the chilling of a beef carcass post slaughter. The methodology followed by Mallikarjunan, P., & Mittal, G. (1994) was adopted in this study. The beef carcass was represented by five two dimensional horizontal cross sections representing five different zones in the carcass, namely the round, the sirloin, the loin, the rib and the chuck. The images of the cross sections in this paper were scanned and digitised and then cross–referenced with measurements from real carcasses to verify the dimensions. Mallikarjunan provided an equation that apportioned the total mass of the carcass to the individual sections.
The finite difference equations were formulated for Cartesian co‑ordinates and coded in Microsoft Excel VBA. The model was used to simulate the conventional chilling regime used by Mallikarjunan in which an ambient temperature of 0.44ºC, an average relative humidity of 85% and an air speed of 0.5 m/s were recorded. The published experimental results were averaged from five carcasses and included temperature histories at the round, sirloin and rib sections for a period of 50 hours in addition to the corresponding averaged cumulative mass loss. The average mass was 155±11kg. Constant values for the thermo-physical properties of thermal conductivity, specific heat capacity and density were determined using COSTHERM.
Energy is lost from the surface of the carcass by convection, radiation and evaporation. Kondjoyan (06) states that evaporation losses can contribute significantly to the total energy losses in the chilling of a meat carcass while radiation losses are of less significance, especially when there are a number of carcasses with similar surface temperatures hanging close together. The heat transfer coefficient of h=20W/m2K, the surface mass transfer coefficient of 14.35x10-11(kg m)/ (kgDMPas) and the moisture diffusivity value of Dm=5.83x10-10 m2/s calculated used by Mallikarjunan were applied in this model.
The model predicted the temperature histories in the round, sirloin and rib sections reasonably accurately but under-predicted the total mass transfer from the carcass.
Gilsenan, R., O'Murchú, N., Fahey, G., Hannon, J., Keane, G. : Development of a Heat and Mass Transfer Model to Simulate the Conventional Chilling of a Beef Carcass, Joint Symposium of Irish Mechanics Society & Irish Society for Scientific & Engineering Computation, Advances in Mechanics, School of Mechanical & Materials Engineering, University College Dublin, Belfield, Dublin 4, Ireland, 2013.