Refrigerant-134a enters the condenser of a residential heat pump at 800 kpa and 35oc at a rate of 0.018 kg/s and leaves at 800 kpa as a saturated liquid. if the compressor consumes 1.2 kw of power, determine

(a) the cop of the heat pump

(b) the rate of heat absorbtion from the outside air.

(A) COP = 2.64

(B) rate of heat absorption= 1.9637 kW

Explanation:

mass flow rate (m) = 0.018 kg/s

work input (Win) = 1.2kW

inlet pressure (P1) = 800kPa

inlet temperature (T1) = 35 degree Celsius

h1 = 271.24 KJ/Kg

outlet pressure (P2) = 800 kPa

outlet temperature (T2) = ?

entalphy (h2) = 95.48 KJ/Kg

The entalphies are gotten from tables for refrigerant 134a at the temperatures and pressures above

(A) COP = Qh ÷ Win

     where Qh  = m(h1 -h2) from the energy balance equation

     Qh = 0.018 ( 271.24 - 95.48 ) = 3.1637 kW

     COP = 3.1637 ÷ 1.2 = 2.64

(B) rate of heat absorption = Qh - Win

    = 3.1637 - 1.2 = 1.9637 kW

nec chapter 5 contains

c. information on special occupancy areas

nec chapter 6 covers

a. special equipment

which of the following rules contain the words shall or shall not and must be adhered to?

b. mandatory rules

which of the following rules identify actions that are allowed but not required and typically cover options or alternative methods?

c. optional rules

which of the following serves as the introduction to the nec and provides an overview of the book?

a. nec article 90

organizations that test products for safety are

c. nrtls

the nec is published by the

a national fire protection association

the nec is divided into

b. 9 chapters

the nec provides informative annexes for

c. informational materials and examples

two terms from nec article 100 that trainees should become familiar with are

b. labeled and listed

explanation: