Isobar Diagrams And: Fill & Download for Free

Okay here goes,Company : TVS BRAKES INDIA PVT LIMITEDSalary : 4.5 llaFinal round : there were 3 interviewers ( 2 managers and 1 HR)M1 : tell me something about yourselfM2: can you please explain your project and draw the circuit diagram of your projectM1 : tell me about your industrial visitsM2: what is Bernoulli's theorem and write down the equationM1: what kind of energy is transformed in brakes in automobilesM2 : what do you know about brakes India ltd,do you know about the products we manufactureM1 : where are our products used, disc brakes are used in front wheels or rear wheels in automobilesM2 : what is a key and which stress is induced in it?..M1 : in case of excessive force which will break first key or shaft ?..H1 : tell me about your parents, relocation is not a problem or notM1 : draw isobaric diagramOverall it was easy and questions were mostly based form resume..Thanks for reading…

When the initial pressure and volume are the same, and the gas expands to the same final volume in both cases, then work done by isobaric process is greater.Work done is area under the p-v diagram. So, area for isobaric is greater, as you can see.You could also prove this mathemarically. Try it, it's real fun!!Edit:I cannot believe there are so many people answering this incorrectly!! It's straightforward from the graph guys!!Anyway, this is for the skeptics :-

Carnot cycle is a ideal thermodynamic cycle with two isentropic and two isothermal processes. To answer your question on why we don't use a Carnot cycle in real world, we need to look at the area under PV diagram for Carnot cycle. The area under PV diagram represents the net work done.Fig: PV diagram for Carnot Cycle for Air. 1-2: Isothermal compression, 2-3: Isentropic compression, 3-4: Isothermal expansion, 4-1: Isentropic expansion. Image taken from: The Stirling Cycle Machines by G. Walker, 1973As we can see from the figure that for Carnot cycle, the area under the PV diagram is small. The reason being that the slopes of an isothermal (PV = const) and isentropic process ([math]PV^{\gamma}[/math]=const), on a PV diagram, are very close to each other. For example, the above plot is drawn for air as working fluid which has [math]{\gamma} = 1.4[/math]. In order to increase the area, we have to increase the pressure by a lot (yes by a lot!..millions of psi), and increase the volume also by a lot!. Now Imagine a giant piston inside a giant chamber operating at 1M psi. Further imagine the weight of such piston and the chamber. This is where Carnot cycle machine becomes useless. Because the real world friction and heat loss will be so high that the net work done by such giant machine will be negative.That's why geniuses like Robert Stirling, Prof. Rankine, George Brayton came up with the thermodynamic cycles which do not have both isentropic and isothermal process in one cycle. For example, Stirling cycle has two isothermal and two constant volume process, Brayton cycle has two isobaric and two adiabatic process. For all of these cycles, the area under PV curve is larger than when compared to Carnot cycle.The reason why Carnot cycle is important is because it places a cap on the maximum efficiency which a machine can achieve. This is because for a Carnot cycle the ratio of work done (i.e area under PV diagram) and heat supplied (i.e area under process 1-2 in above PV diagram) is maximum. Hence it has the maximum efficiency.By now, if you are not convinced, try plotting Striling cycle and Carnot cycle for air and given values of Pressure & Volume on a PV diagram.Njy!