Hi all,
I'm seeking some opinion on the best best way to warm milk for my rfid calf feeder? At the moment I have a drum full of water with a copper coil in it that the milk flows through, the water is heated by a fish tank heater (300w) and the milk comes out warm.
It seems a waste of energy to run the heater 24hrs so I would like to run the milk through a stainless steel tube that heats up to warm it. It would then only need to run while a calf is feeding.
As far as I can see I've two options for heating the tube? One is to wrap a heater element round the pipe and use PWM to control the heat output.
The other is to put the tube in a coil and use induction heating to heat the tube.
I'm going to use a couple of thermocouples to make sure the milk isn't too hot,(if they don't agree with each other everything will stop, don't want to harm the calves!).
I've done some basic sums based on maximum milk flow and temperature difference and the most power I could require is a bit less than 300w as this is absolute maximum I think 300w will be enough to allow for losses?!
This will all be controlled with a 18fxxxx PIC so I have pleanty of A/D channels and PWM avalible.
I've not had much to do with power switching before , to me induction heating the tube seems attractive, whichever way I go I'm going to need power transistors.
What do folks think? Basicly I'm looking for the pros and cons of each method. (or a new idea I've not thought of!)
Cheers Geoff
I'm seeking some opinion on the best best way to warm milk for my rfid calf feeder? At the moment I have a drum full of water with a copper coil in it that the milk flows through, the water is heated by a fish tank heater (300w) and the milk comes out warm.
It seems a waste of energy to run the heater 24hrs so I would like to run the milk through a stainless steel tube that heats up to warm it. It would then only need to run while a calf is feeding.
As far as I can see I've two options for heating the tube? One is to wrap a heater element round the pipe and use PWM to control the heat output.
The other is to put the tube in a coil and use induction heating to heat the tube.
I'm going to use a couple of thermocouples to make sure the milk isn't too hot,(if they don't agree with each other everything will stop, don't want to harm the calves!).
I've done some basic sums based on maximum milk flow and temperature difference and the most power I could require is a bit less than 300w as this is absolute maximum I think 300w will be enough to allow for losses?!
This will all be controlled with a 18fxxxx PIC so I have pleanty of A/D channels and PWM avalible.
I've not had much to do with power switching before , to me induction heating the tube seems attractive, whichever way I go I'm going to need power transistors.
What do folks think? Basicly I'm looking for the pros and cons of each method. (or a new idea I've not thought of!)
Cheers Geoff