Been looking at this question for a while and can't figure it out.
An aluminium furnace is fuelled with propane gas. The furnace is loaded up with 4 aluminium ingots each of mass 22.5 kg.
The question is:
If 2.1 kg of propane is used to complete the melting process calculate the efficiency of the furnace’s heat transfer process.
Calorific value for propane 49.93 MJ/kg.
The Attempt at a Solution
From an earlier question I worked out the following:
660 – 20 = 640
22.5 x 0.91 x 640 = 13,104 kJ
Melting point = 13,104 kJ
321 x 22.5 = 7,222.5
Boiling point = 7,222.5 kJ
Total energy = 13,104 + 7,222.5 = 20,326.5 kJ
So far I've played around with the values:
49.93 x 22.5 = 1,123.425 MJ or kg
49.93 x 2.1 = 104.853 MJ or kg
Do I have to replace the original melting point answer with one of the above answers?
I'm very new to physics so any help very much appreciated.