Question

A smelting fumace is fuelled with propane gas to melt Aluminium ingots (shown below) for engine sump manufacturing similar to that shown in the image below. The furace is loaded up with 100 aluminium ingots each of mass 15 kg. (a) Calculate the total energy that must be supplied by the fumace to bring the ingots up to melting point and then to melt the ingots completely. Before being placed in the furnace the ingots are stored at 20°C. Use the data provided below. (b) (c) If 50 kg of propane is used to complete the melting process calculate the efficiency of the furnace's heat transfer process. A standard aluminium ingot is 1000 mm in length at 20°C. When the ingots reach a temperature of 500°C. Calculate: The increase in length due to the thermal expansion of an ingot assuming the ingot is free to expand The induced force in an ingot assuming it has become jammed in the fumace and is NOT free to expand DATA: Melting point of aluminium Specific heat capacity for aluminium : Latent heat of melting for aluminium (L): Modulus of elasticity for aluminium: Coefficient of linear expansion for aluminium Calorific value for propane Ingot cross sectional area 600°C 0.01 kJikak 321 kJika 89 Pa 22.2 x 100 49.93 MJ/kg 0.019 m

Answer 1

Griver dato in q Alingots, n=100 of each inget, m= 15kg Tin = 26c = 293k Tout = 660°c 933º k specific heat of A1, (p = 0.91 Lakat head of melting for AI, (Lt) = 321 llig (a) Energy required, Erea Ever Sensible heart latent here. mc Crot & Lakent hear) = 100x1's (0.91(933-293) + 321) 1355100 KJ Erea = 1355.1 MI) (5) so kg Propane is used, Esop = supply energy a mas of propane x Calorida value sox 49.93 MJ/kg so y49.93x106 Esupply = 2496500 kJ = 2496.5 MJ Efficiency of fornace heat transfer process, in m Erew 1355.1 Esupply = 0:5427 2496.5 :542747

(c) Ingat length, locomm Ttinal - Sosc = 773°k Tin=28c =293k La = 22 2x15tpac enga Crom-dlctim orea, A=0.019 m² (1) gncrease in length due to thermal expansion, St S l = ld DT x(500-20) 1 X 22 2x156 = 10.66X163 10.6 mm (i) z ingat is Jammed, not free to expand, it will be under compressive stress due to expansion E - LDT 읕 - КАТ E =69 Gpa =LAT F = LATEA = 22.2 flotx (500-20) x69x109 x0.019 = 13.97 xlos 13.97 MN