Heat transfer Flashcards
Air is best heated with steam in a heat exchanger of
double pipe type with fin on air side.
Black liquor generated during paper manufacture is concentrated in a
multiple effect evaporator
Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively
C/E
Reynold’s analogy states that
Nst α f
With increase in temperature, the thermal conductivity of non-metallic amorphous solids
increases
Fourier’s law applies to the heat transfer by
conduction
In the equation Q = UAΔt; Δt is
logarithmic mean temperature difference
With increase in porosity, the thermal conductivity of a solid substance
decreases
For an ideal black body
absorptivity = 1
For every 10% increase in the excess air; the fuel consumption increases by __________ percent.
0.1
Main component of sewage gas produced during anaerobic decomposition of organic waste (by suitable bacteria) during sewage disposal is
CH4
A fuel containing carbon and carbon monoxide (but containing no hydrogen or its compounds) is burnt in pure oxygen at constant pressure. Its gross calorific value as compared to net calorific value will be
Same
Initial pressure of oxygen introduced into the ‘bomb’ of the bomb calorimeter for determination of calorific value of coal/fuel oil may be around __________ atm.
25-30
Pure carbon is completely burnt in oxygen. The flue gas analysis is 70%CO2, 20%CO and 10%O2. The percent excess oxygen used is
0
__________ of the coal is the basis for Seylor’s coal classification.
Ultimate analysis
Main constituents of benzol are
benzene, toluene & xylene.
“Overfire burning” in a furnace is a phenomenon characterized by the
burning of carbon monoxide and other incombustibles in upper zone of furnace by supplying more air.
The calorific value of ‘LPG’ (50% propane + 50% butane) is about __________ kcal/Nm3.
25, 000
petrographic constituents of coal is non-coking
Fussain
__________ has the widest inflammability limit (explosion limit) of all the gases.
Acetylene
In flue gas analysis by Orsat’s apparatus, carbon dioxide is absorbed by
potassium hydroxide.
Caking index of the coal blend used for the manufacture of metallurgical coke should be around
21
Proximate analysis of coal determines its __________ content.
moisture, volatile matter, ash & fixed carbon.
Presence of free moisture in coal is most disadvantageous during
its pulverization (as it requires more power).