1. The problem statement, all variables and given/known data I want a detailed understanding of the temperature drop of a boiler when water is lost from a leak. I have a temperature recording of a leak that lasted for an hour and caused the temperature to drop from 170oC to 150oC when 2.55m3 of water was lost. I have tried using steam tables to understand the temperature drop but my calculations show a slight temperature increase instead of decrease, so obviously my approach is wrong. I would appreciate some guidance on the correct way to calculate the theoretical temperature drop. This is the approach that I tried: 2. Relevant equations Steam table: View attachment 123054 3. The attempt at a solution Assumptions: 1m3 of water weighs 1 tonne at the temperatures under consideration. No energy was added to or removed from the system other than the energy in the lost water and work done to push it out of the leak hole. Initial conditions: 6.55m3 of water and 2.35m3 of saturated steam at 8 bar (116 psi). From steam table www.engineeringtoolbox.com/saturated-steam-properties-d_457.html steam density is 4.16kg/m3, so mass of steam is 2.35 * 4.16 = 9.78kg Enthalpy of water + steam is 6.55 * 721 + 9.78 * 2.77 = 4723 + 27 = 4750MJ Energy lost in the 2.55t of hot water that leaked out: Water was cooling during the leak. Assume average temperature was 160. At that temp the specific enthalpy is 676, so total lost enthalpy is 1720MJ. Work done in pushing the water out of the hole: Average pressure is 6.5bar = 0.65MP = 0.65 MN/m3 0.62MN moving 2.55m = 1.6MJ ------- Negligible End conditions: After the water leak the enthalpy of the system is the original enthalpy less the losses: 4750 - 1720 - 2 = 3028MJ. To find the temperature of the system we search the steam table for the temperature of a system with an enthapy of 3028MJ and having 4t of water and 4.9m3 of steam. We find this at 175oC, which is hotter than the initial temperature !!?? Something is wrong.