Refrigerators
Problems
practice
- Determine the following quantities for a window mounted, residential heat pump described in the table below:
- the heat…
- extracted from the environment per hour when the device is operated in heating mode
- exhausted to the environment per hour when the device is operated in cooling mode
- the real coefficient of performance…
- in heating mode
- in cooling mode
- the ideal coefficient of performance for a 22 °C inside temperature and…
- a −2 °C outside winter temperature
- a +34 °C outside summer temperature
- the velocity of the air blowing into the room when the device is operated in either mode
Residential heat pump heating mode cooling mode both modes heating capacity
7.9 MJ/hourcooling capacity
10 MJ/hourvolts rated
115 voltsheating amps
7.6 ampscooling amps
7.8 ampsair circulation
8.1 m3/minuteheating watts
743 wattscooling watts
812 wattswidth
66 cmmoisture removal
0.90 liter/hourheight
40 cmdepth
74 cm - the heat…
- Write something else.
- Write something different.
- Write something completely different.
numerical
- One millimole of a monatomic, ideal gas is run through a four-step cycle as shown in the table below.
- Sketch the cycle on a PV graph.
- Determine the absolute temperature of the gas when it is in states A, B, C, and D.
- Determine ΔU, Q, and W for each segment of the cycle (A→B, B→C, C→D, D→A) and for the cycle as a whole (ABCDA). Include an algebraic sign with each answer. (Zero values do not get a sign.)
- Determine the real coefficient of performance assuming the cycle is used as a refrigerator.
- Determine the ideal coefficient of performance for this refrigerator.
- How are the answers to the last two questions in apparent conflict? Why are they?
A four step closed cycle state A B C D P (kPa) 100 624 312 100 V (m3) 24 × 10−6 8 × 10−6 8 × 10−6 16 × 10−6 T (K) path A→B B→C C→D D→A ABCA description adiabatic isochoric adiabatic isobaric whole cycle ∆U (J) Q (J) W (J)