Problem 108HP

A farmer runs a heat pump with a motor of 2 kW. It should keep a chicken hatchery at 30°C; the hatchery loses energy at a rate of 0.5 kW per degree difference to the colder ambient. The heat pump has a COP that is 50% that of a Carnot heat pump. What is the minimum ambient temperature for which the heat pump is sufficient?

Spencer Kociba CHEM 101 Lecture 11/15/16 THERMOCHEMISTRY ● Enthalpy ○ Represented as ΔH ○ Internal energy + pressure*volume ■ We will mostly be concerned with constant pressure. This is where the formula ΔH = ΔE + PΔV comes from ○ ΔH = q (enthalpy=heat gained or lost in the system) ● Properties of Enthalpy (ΔH ) ○ ΔH is directly proportional to mass ○ ΔH for a reverse reaction is equal in magnitude (quantity) but opposite in sign for the forwards reaction ○ Hess’s Law: ΔH is independent of the number of steps involved ■ If Reaction(1) + Reaction(2)=Reaction(3), then ΔH =3ΔH + 1H 2 ● Endothermic reactions ○ Gains heat from sur