A concrete highway is built of slabs 12 m long (at 15◦ C). How wide should the expansion cracks between the slabs be (at 15◦ C) to prevent buckling of the range of temperature is -30◦ C to +50◦ C?

Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 mpa and -10°c at a rate of 0.05 ka/s and leaves at 0.8 mpa and 50°c. the refrigerant is cooied in the condenser to 0.72 mpa and 26'c. it is then throttled to 0.15 mpa. sketch the t-s diagram for the system and evaluate: 6) the rate of heat removai from the refrigerated space (kw), it) the power input to the compressor (kw), ii) the isentropic efficiency of the compressor (%), and iv) the cop of the refrigerator.

Heat transfer by is the fastest mode of heat transfer that requires no intervening medium. a)-conduction b)-convection c)-radiation d)-conduction and convection

Natural gas (95 percent methane and 5 percent ethane by volume) flows through a 90 cm diameter pipeline with a velocity of 3 m/s. the pressure in the pipeline is 700 kpa, and the temperature is 15°c. calculate: (a) the mass and volumetric flow rates in this pipe.