Increasing Airflow through Condenser.
The new DC only compressor fridge I will soon have in my possession has a 92 mm computer muffin fan pulling air through only a portion(~85%) of the ~120mm tall condenser. It then blows this warmed a...
Forum Discussion
The Danfoss BD35 & BD50 compressors are internally driven by what are basically 3 phase motors that can be run at any speed between 2000 rpm & 3500 rpm depending on the frequency of the signal applied to the windings. The Danfoss controller that is attached to the compressor housing converts the incoming 12 or 24 volt dc power into the modified dc that is needed to run the motor, & the speed of the motor is determined by the value of a resistor connected in series with the thermostat lead. Manufacturers may mount resistors somewhere in the thermostat circuit to force the compressor to run at a speed predetermined for the size & type of evaporator & condenser used. This avoids over-capacity & component stress & also reduces current draw to an safer, more acceptable level, but is not easily adjustable. If a thermostat is connected directly to the controller, without any resistor, the compressor will run at the slowest speed, 2000 rpm.
You won't cause a problem by installing a bigger fan, but it's unlikely that you'll see much benefit from it. I have Danfoss systems operating in customer's boats with stock fans and installed in spaces with no additional ventilation with no issues. It does make a difference which direction the airflow is going, and the engineers have decided that even a small amount air blowing on the compressor has some effect on heat disapation from the compressor.
There are also aftermarket modules that can be connected to the modules that let you manually control compressor speed, but I have no experience with them. The brunt of my service work is marine air conditioning and I haven't had a need to do a lot of research on the aftermarket stuff that's out there. My thought is that it works fine the way it comes from the factory, but there is always someone who can't resist tinkering.
You won't cause a problem by installing a bigger fan, but it's unlikely that you'll see much benefit from it. I have Danfoss systems operating in customer's boats with stock fans and installed in spaces with no additional ventilation with no issues. It does make a difference which direction the airflow is going, and the engineers have decided that even a small amount air blowing on the compressor has some effect on heat disapation from the compressor.
There are also aftermarket modules that can be connected to the modules that let you manually control compressor speed, but I have no experience with them. The brunt of my service work is marine air conditioning and I haven't had a need to do a lot of research on the aftermarket stuff that's out there. My thought is that it works fine the way it comes from the factory, but there is always someone who can't resist tinkering.
