Question

An electrical heater is a form of sensible heating process, and heats 0.1 m/s of air from 15°C and 80% RH to 50°C? The barometric pressure is 101.325 kPa. Using the psychrometric chart given, determine the heater wattage.

Answer 1

Answer:

heater wattage = 4.32 kW

Explanation:

given data

volume flow rate of air = 0.1 m³/s

temperature t1 =  15°C

temperature t2 =  50°C

relative humidity RH = 80%

pressure = 101.325 kPa

to find out

heater wattage

solution

we will get here h value from psychometric chart with the help of temperature

that is

h1 = 37 kJ/kg

and

h2 = 73 kJ/kg

and v1 = 0.829 m³/kg

so here heater wattage formula is

heater wattage = m ( h2 -h1)    ......1

here m is

m = V/v1 = 0.1 / 0.819 = 0.12 kg/s

so from equation 1

heater wattage = 0.12 ( 75 -39 )

heater wattage = 4.32 kW