Question

23.) coffee as quickly constraints would you think must be met? You are asked to design a stove-top coffee maker with the goal of cooking the possible. What objective would you choose, and what as Use the charts below to pick a suitable material. Explain your selection. (5 marks) Cast Al-alloys Nickel-based superalloys 500 Tungsten alloys Сopper 200 Stainless steel 100 50 Low alloy steel 20 Cast iron, gray 10 Lead alloys 1000 10 100 Thermal conductivity (Wim.C) Cast iron, gray Cast Al-alloys Copper Stainless steel Non-toxic. Low alloy steel Tungsten alloys Sightly toxic Lead alloys Тоxe 10 0.5 2 20 50 Price (NZD/kg) Toxicity rating Young's modulus (GPa)

Answer 1

The primary objective here is to design a coffee maker which makes coffee as soon as possible. Unlike the automatic ones available nowadays, this one needs to be a stove -top one. With this clear at the back of mind, we need to carefully analyse our requirement.

For coffee to be made as quickly as possible, we need equipment that transfers heat fast. The property which governs such a process in any material is thermal conductivity(k). And of course, since heat is being transferred, there will be multiple expansions and contractions so strength or the ability of the material to withstand such changes, Young's modulus(Y), should be looked into. When we manufacture something, we need to take care of its environmental viability and commercial viability. For a country like India, commercial factor plays a huge role given the state of minds of the masses here.

Taking these factors into account and from the charts, we can conclude that cast Al alloys will serve the purpose, taking all the factors into consideration. Tungsten for that matter has a higher k value, but this is expensive. Cast Al alloys have good k values, good Y values, non-toxic and cheap. Copper can also stand a chance, in fact, it would make your coffee in no time but money constraint would restrict its selection, hence cast Al alloys are best suited.