Quote Originally Posted by Segei View Post
I agree with 1. Only question is How can we do that? Increased insulation, fast acting doors, modify lightning... What is the payback for these improvement? Not so often you can get acceptable 2 years.
#2 and 4 contradict each other. Reduce compression ratio means minimum condensing pressure and maximum suction pressure. To achieve that, aux(pumps, fans..) should be operated at full capacity. Condensing pressure should be optimum(not minimum) and suction pressure should be optimum as well.
I didn't get about transport losses.
These rules apply to all refrigeration including AC
So looking at load reduction, i gree with your methods, but what about using shading to remove solar gain, or wetted surface to reduced TD across insulation.
Compression ratio we can agree on principle (I think), this normally is limited to the compressor limits. What is required is exansion devices that are able to control to the min and max of the compressor and system limits.
Re the aux, are you using fans and pumps that are at the optimum on the perfromance curves, are these driven high efficient moters, do they turn off or down when load/compressor limits reduces/reached.
Transport losses, relates to non useful heat gain (poorly insulated suction lines) and excessive pressure drops in refrigeration and fluid lines.
For example we have a water flow of 'X', ideally we need a 2" pipe, but we know if we up the pump pressure a bit we can fit a 1 1/2" line. This is done all of the time, quite good reductions installation cost (pipe, labour, valves insulation) poor for efficiency.
Then we come to payback, this is where all the best engineering the world falls over. At what point is advances to high. This depends upon the client, if a goverment dept, then then they should be seen to being the right thing (long payback are acceptable)
Commercial clients need to ensure a return to their sharholders, again this depends upon the type of business and how they precieve their long term business models. For example in NZ agri business in the main stay, but is quite fickle (produce price go up and down a lot) so most need devices that have shport term paybacks. Verses say a building which may have a constant return over 20 years.
Domestic refrigeration (including AC) which is a massive industry, should be improved by means of minimum performance regualtion.