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Consider the following statements for cooling towers: 1. Cooling tower is an artificial device used to cool the hot cooling water coming out of condenser more effectively. 2. The amount of water usually lost with induced draft cooling tower ranges from 5% to 6% by evaporation. 3. The amount of water usually lost with induced draft cooling tower ranges from 7% to 8% by drift losses. 4. The rate of evaporation of water and its cooling effect on the remaining water depends upon the relative humidity of air passing through the tower. Which of the above statements are correct?
Concentrated fermentation liquid containing 20% (w/w) gluconic acid from an evaporator has a flow rate of 2000 kg/h and a temperature 90 °C. It needs to be cooled to 6 °C in a heat exchanger with cooling water. The cooling water has a flow rate 2700 kg/h and an initial temperature 2 °C. If the cooling water leaves the heat exchanger at 50 °C, what is the rate of heat loss from gluconic acid solution to the surroundings? Assume the heat capacity of gluconic acid is 0.35 cal/g-°C-1.
A polished metal pipe 5 cm outside diameter and 370 K temperature at the outer surface is exposed to ambient conditions at 295 K temperature. The emissivity of the surface is 0.2 and the convection coefficient of heat transfer is 11.35 W/m2 degree. Calculate the overall coefficient of heat transfer by the combined mode of convection and radiation
The determination of a value of Nusselt number or the convective film coefficient forms a basis for the computation of heat transfer by convection. Towards that end, following approaches have been suggested (i) Non-dimensional analysis and experimental correlations (ii) Hydrodynamic concept of velocity boundary layer (iii) Reynolds similarity between the mechanism of fluid friction in the boundary layer and the transfer of heat by convection Identify the correct one
In a surface condenser, the water flowing through a series of tubes at the rate of 200 kg/hr is heated from 15 degree Celsius to 75 degree Celsius. The steam condenses on the outside surface of tubes at atmospheric pressure and the overall heat transfer coefficient is estimated at 860 k J/m2 hr degree. Find the number of transfer units of the heat exchanger. At the condensing pressure, stream has saturation temperature 0f 100 degree Celsius and the latent heat of vaporization is 2160 k J/kg. Further, the steam is initially just saturated and the condensate leaves the exchanger without sub-cooling i.e. only latent heat of condensing steam is transferred to water. Take specific heat of water as 4 k J/kg K
The rate equation used to describe the mechanism of convection is called Newton’s law of cooling. So rate of heat flow by convection doesn’t depend on
A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as
A heat exchanger with heat transfer surface area A and overall heat transfer coefficient U handles two fluids of heat capacities Cmax and Cmin. The number of transfer units (NTU) used in the analysis of heat exchanger is specified as
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in meters, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in meters, and d = Dia. of rope in meters)
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, $$l$$ = Length of arm in meters, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Diameter of brake drum in meters and d = Diameter of rope in meters)