First Law of Thermodynamics

Energy can not be created or destroyed and all forms of energy are mutually convertible

Conversion – Electrical energy to thermal energy

1 W = 3.413 Btu

1 kW= 3413 Btu

Electrical energy to Mechanical energy

746 Watts = 1 hp

Mechanical energy to Electrical energy

1 hp = 746 Watts

33, 000 ft/lb/hr = 1 Btu/hr

Thermal energy to Electrical energy

1 Btu = 0.293 Watts

Thermal energy to Mechanical energy

1 Btu = 0.000393 hp

Second law of Thermodynamics

Heat will flow from one area to another of lower temperature

Specific heat – the amount of heat required to change the temp. of 1 lb.

of a substance 1 F

Btu British thermal unit – the amount of heat required to change the temp. of 1 lb of water 1 F

Sensible heat – heat which causes a change in temperature

Latent heat – heat energy required for a substance to change state (solid, liquid, gas)

Sensible heat Formula

Qs = Mass (lb) * SpHt * delta T(F)

Qs = the quantity of sensible heat in Btu

SpHt = the specific heat of a substance

Delta T = the change in temp F

Latent heat Formula

Ql = mass(lb) * latent Ht

Ql = the quantity of latent heat in Btu

Latent Ht = a substances latent heat

Total Heat Formula – Enthalpy = Qs + Ql