Originally Posted by Nick D
I do and turn the fridge on it makes the engine revs drop to almost cuttting off and dose not get cold.it is an eutectic fridge that works off the engine,any idea what is causing this.
Welcome to CF, Nick.
I assume you've an engine-driven refrigerator
compressor, probably with an electro-magnetic clutch
What's the power
rating of that refrigerator
compressor? I'd guess it to be somewhere in the range 3/4 horsepower (0.6 kW) to 2 hp (1.5 kW).
What's the power
rating of your auxiliary engine at the engine speed (rpm) at which you're engaging the refrigerator compressor?
If your yacht's auxiliary engine is only at idle, producing perhaps 3 or 4 kW, then the load from your (perhaps) 1.5 kW compressor would of course drop engine rpm
. And perhaps even bring a diesel
engine - if that's what you have - close to lugging. If you increase the engine rpm
does the engine respond?
As for your fribge not getting cold, for how long have you run the engine-driven refrigerator compressor? What are the heat loads associated with your fribge: what is it's ambient temperature? what's the volume of the fribge? at what temperature is the thermostat set?
The jobs you're asking of your engine-driven refrigerator compressor are:
first, to pull the temperature of the holding plate down from ambient to some sub-zero temperature;
second, to respond to a signal from the fridge thermostat to electro-magnetic clutch to disengage; and
third, after heat from your fribge has warmed your holding plate up again (as your fribge or icebox
has cooled down), for the thermostat to signal the electro-magnetic clutch to engage the refrigerator compressor again.
I don't know your ambient temperature and so on, but I'd guess that those three steps might take as long as 45 or 60 minutes.
For how long have you run your refrigerator compressor?
Does your compressor have a sight glass through which you might be able to see a bubble?
What heat exchange mechanism do you have? Do you for example have a raw-water cooled heat exchanger
or a fan-forced air radiator? At what temperature is the sea-water? What is rate of flow of the sea-water?