Thermal Physics

Thermodynamics

Heat Pump

  • A refrigerator or an air-conditioner unit is an example of a heat pump



    • Heat pumps normally flow from cold to hot

QH = QC + W

Heat transfers from the cold reservoir Qc into the hot resavour

This requires W, which is converted to heat

Therefore QH consist of the heat flowing out of the cold reservour QC and the work done on the heat pump W.

QH = Heat transfer to the hot reservoir


Qc = heat transfer to a cold reservoir


W = Work done to increase heat

Gasses

PV = NkT

P= Pressure (Pa)
V= Volume (m3)
N= Number of molecules
K= Boltzmann constant
T= Temperature (k)

P1V1 = p2V2

P1 = 125 kPa

P2 = 100 kPa

V1 = 200cm3

V2 = (125 x 200)/ 100 = 250cm3

Assuming the temperature remains constant

Isothermal process: A change in the system i.e. Composing or expanding the gas where the temperature does not change.


Adiabatic process: An adiabatic process is one where no heat enters or leaves the system (opposite to an isothermal process because the temperature will change).


Laws of thermodynamics

Efficiency = W/Qin

Qin = how much comes in

W= work

Efficiency = 1 - Qout/Qin

Efc = 1 - TC/TH

Tc = Temperature of cold reservoir


TH = Temperature of hot reservoir


Kalvin = +273.15

What U, Q and W mean in relation to the human body

W - translates to heavy exercise and even sleep

Q - Qin is the food we eat and that food is used to provide us with energy and in tern translates into work.

U - Your body storing food to convert into energy at a later date is and example of internal energy