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Interview Q/A

Q1. Use of Hagen Poiseuille equation .give its formula also and what happen to friction factor if vel is double and length is D.

▶️Hagen–Poiseuille  gives the pressure drop in an incompressible  and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant cross section.

Doubling this average velocity doubles the number of collisions between gas molecules and the walls of a container. Thus the pressure quadruples. … More molecules hit the sides of the container, each with a greater impulse, so that the pressure increases.


Q2.Characteristic curve for head vs flow rate and efficiency vs flow rate.


Q3.Peak efficiency point.

▶️As we see  from the graph for same flow rate ,at best efficiency point we use less value of head whereas at peak efficiency point value of head is more. Moreover after peak efficiency point ,leakage occurs and if any disruption occurs then pump get damaged.


Q4. Define LMTD and its significance.

▶️LMTD is the logarithmic mean of temperature difference of the fluids at both the sides of the heat exchangers.

It is introduced due to the fact, the temperature change that takes place across the heat exchanger from the entrance to the exit is not linear.

It is the driven force for the heat exchange between the two fluids. As the LMTD value increases, the amounts of heat transfer between the two fluids also increase. 

Its value is used for calculating the heat duty of the heat exchanger. The formula is:

 Q = U * A * LMTD


Q5.Why counter current heat exchanger is better than co-current heat exchanger?

▶️Because for same heat duty counter current heat exchanger requires less surface area.


Q6.Which type of heat exchanger is widely used in industries.

▶️Shell and tube heat exchanger.


Q7.Difference between natural and forced convection.

▶️Convection is called forced convection if the fluid is forced to flow over the surface by external means such as a fan, pump, or compressor etc. In contrast, convection is called natural (or free) convection if the fluid motion is caused by buoyancy forces that are induced by density differences due to the variation of temperature in the fluid.

The heat transfer coefficient(h) is higher in forced convection as compared to its value in free convection.

In forced convection we consider the inertia effects while in free convection we consider buoyancy effects.

Reynold’s no. comes into picture while discussing forced convection and grashof’s no. comes into picture while discussing free convection.


Q8. How many companies do visit in your campus.

▶️Many companies such as UOP honeywell,HMEL,Relience,Jubilent lifesciences,Vedanta,Glenmark,Bechtell,Exxon mobil,Cairn,Infosys,Aakash,Licious,Nestle and many more companies do visit in our department.


Q09. What does a design engineer do.

▶️A career as a design engineer is all about transforming ideas into real products.

Design engineers study, research and develop ideas for new products and the systems used to make them. They also modify existing products or processes to increase efficiency or improve performance. They work on almost every consumer product imaginable for large-scale production, from telephones and medical equipment to kitchen appliances and car engines.

Design engineers are not only concerned with making products that look good and are easy and safe to use: they are also concerned with ensuring that the product can be made cost-effectively and efficiently.

Design engineers can also move into management roles such as project management and new business development.


Q10.What are design companies.

▶️

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