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Download lecture notes-growth kinetics-3-heat evolution
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Batch Growth Heat generation by microbial growth For actively growing cells, the maintenance requirement is low, and is directly related to . The heat of combustion of the substrate is equal to the sum of the metabolic heat and the heat of combustion of the cellular material. H s 1 H c Y Y X /S H s H Is the heat of combustion of the substrate (kJ/g substrate) Y X / S is the cell mass yield per substrate consumption (g cell/g substrate) H c is the heat of combustion of cells (kJ/g cells) 1 is the metabolic heat evolved per gram of cell mass produced Y (kJ/g cells) H Batch Growth Heat generation by microbial growth Re-arrange the above equation: H s 1 H c YH YX /S The higher degree of oxidation of the substrate has lower amounts of heat released: 1/YH Glucose: ethanol: Methanol: Methane: Unit! 2.38 kcal/g cell produced 5.55 kcal/g cell produced 8.33 kcal/g cell produced 16.34kcal/g cell produced Batch Growth Heat generation by microbial growth H s 1 H c YH YX /S The total rate of heat evolution in a batch fermentation QGR is 1 Q V X GR L net Y (kJ/h) H X is the cell mass concentration (g/L); V L is the liquid volume (L) H removal: by circulating cooling water through a cooling coil or cooling jacket in the fermentation.