Water flows through a vertical contraction from a pipe of diameter $$d$$ to another of diameter $$d/2$$ (see Figure). The flow velocity at the inlet to the contraction is $$2m/s$$ and pressure $$200$$ $$kN/{m^2}.$$ If the height of the contraction measures $$2m$$, then pressure at the exit of the contraction will be very nearly

It is proposed to coat a $$1mm$$ diameter wire with enamel paint $$\left( {k\,\,\,\, = 0.1W/m} \right.$$ - $$\left. K \right)$$ to increase heat transfer with air. If the air side heat transfer co-efficiency is $$100$$ $$W/{m^2}K,$$ the optimum thickness of enamel paint should be

Two fluids, $$A$$ and $$B$$ exchange heat in a counter-current heat exchanger. Fluid $$A$$ enters at $${420^ \circ }C$$ and has a mass flow rate of $$1$$ $$kg/s.$$ Fluid $$B$$ enters at $${20^ \circ }C$$ and also has a mass flow rate of $$1$$ $$kg/s,$$ Effectiveness of heat exchanger is $$75\% $$. Determine the heat transfer rate and exit temperature of fluid $$B.$$ (Specific heat of fluid $$A$$ is $$1$$ $$kJ/kg$$ $$K$$ and that of fluid $$B$$ is $$4$$ $$kJ/kgK$$).

In computing Wilson’s economic lot size for an item, by mistake the demand rate estimate used was $$40\% $$ higher than the tree demand rate. Due to this error in the lot size computation, the total cost of setups plus inventory holding per unit time, would rise above the true optimum by approximately