cabellos2
Mar2-09, 07:58 AM
I have a problem whereby sludge of quantity 1000 kg/day is required to fill an anaerobic digester tank. The sludge enters at 20deg and is heated to 35deg. With refernece to this link http://books.google.co.uk/books?id=D...obic+digestion
it can be seen that if I have a quantity of 1000kg/day then the formula shown can be used to calculate the heat energy required.
My problem is understanding the difference between this value of heat energy and the value Q for heat transfer in a heat exchanger. As Q = m*cp*(T2-T1) if I have a set flow velocity through the exchanger pipe of 1 m/sec and a pipe diameter my mass flow rate m works out greater than the 1000kg/day and thus my value of Q heat required is greater.
MAIN QUESTION >>>>
Does this mean that the mass flow rate through the exchanger dictates how much how much heat energy I require and not the amount suggested by the equation in the book link which does not take into account pipe dimensions and flow velocities??
Thanks for the help
it can be seen that if I have a quantity of 1000kg/day then the formula shown can be used to calculate the heat energy required.
My problem is understanding the difference between this value of heat energy and the value Q for heat transfer in a heat exchanger. As Q = m*cp*(T2-T1) if I have a set flow velocity through the exchanger pipe of 1 m/sec and a pipe diameter my mass flow rate m works out greater than the 1000kg/day and thus my value of Q heat required is greater.
MAIN QUESTION >>>>
Does this mean that the mass flow rate through the exchanger dictates how much how much heat energy I require and not the amount suggested by the equation in the book link which does not take into account pipe dimensions and flow velocities??
Thanks for the help