Engineering High School

The structure of a house is such that it loses heat ata rate of 3800 kJ/h per8C difference between the indoors andoutdoors. A heat pump that requires a power input of 4 kWis used to maintain this house at 248C. Determine the lowestoutdoor temperature for which the heat pump can meet theheating requirements of this house.

Answers

Answer 1

Answer:

The lowest outdoor temperature for which the heat pump can meet the requirement of the house is -9.6°C

Explanation:

The coefficient of performance of a heat pump, COP, is given by the relation;

[tex]COP_{hp} = \dfrac{T_2}{T_2 - T_1} = \dfrac{Q_1\times (T_2 - T_1)}{\Sigma W}[/tex]

The rate of heat loss [tex]\dot Q_1[/tex] = 3800 kJ/h = 3800 ×1/60 × 1/60 kJ/s = 1.06 kJ/s

The power input = 4 kW = 4 kJ/s

The temperature indoors = 24 + 273.15 = 297.15 K

Therefore, we have;

[tex]COP_{hp} = \dfrac{297.15}{297.15- T_1} = \dfrac{1.06 \times (297.15- T_1)}{4}[/tex]

4×297.15= (297.15- T₁) × 1.06×(297.15- T₁)

Which gives;

18/19·T₁²-627.32·T₁+92014.97=0

(T₁ -263.59)·(T₁ - 330.71) = 0

The solutions are;

T₁ = 263.59 K or T₁ = 330.71 K

The lowest temperature = 263.59 K which is -9.6°C

The lowest temperature = -9.6°C.

Related Questions

The gear lube level is being checked in a manual transmission. Technician A says it should run out when the plug is removed. Technician B says that some transmissions use motor oil as gear lube. Who is correct?

Answers

Answer:

Both technician A and B are correct

Explanation:

The function of the gear lube drain plug is to drain the automatic transmission fluid from the gear box

Although motor oil is for the engine, motor vehicle transmission uses different oil types as the transmission system or  automatic transmission system (ATF) operates in an closed system environment it is free from fuel contamination that motor oil absorbs

As such depending on the specification, manual transmission oil can range from hypoid oil, motor oil or automatic transmission oil.

Could an able-bodied person receiving all or most of their income from government transfer payments achieve earned success? Why or why not?

Answers

Answer:

yes and no because if he transferred he has a major reason for doing so but if he doesn't its his own piece of cake and another reason why he transferred is to protect and keep his money and account and belongs safe

Am I the only one who cannot see the answers?? Does anybody know how to solve this?

Answers

Answer:

no, it seems that everyone is having the same issue. If you use the app you can still find the answers and see them.

Explanation:

which of the following is not one of the common types of traction loss?

A. ROLL
B. YAW
C. PITCH
D. FORWARD

Answers

Answer: Forward So it's D

Answer:

It's forward :)

Explanation:

Please what is the name of this tool​

Answers

Answer: it’s called a saw or see saw

Explanation: it works by cutting a tree, wood, tile, etc.

The speed limit is posted in most areas, but, if not, the ___________ speed limit will be in effect. A. implied B. default C. conditional D. none of the above

Answers

Answer:

The answer is B (default).

In the event of a crash, Personal Injury Protection (PIP) coverage pays toward the medical costs for _____.
A. any injuries you cause to others
B. any injuries that are not your fault
C. your injuries if you are not at fault
D. your injuries, regardless of who's at fault

Answers

Answer:

The answer is D. Your injuries, regardless of who's at fault.

2. Technician A says that checking ambient temperature as part of an AC performance test is unnecessary. Technician B says that if the AC compressor hasn't
been operating, the high-side pressure should be high and the low-side pressure should be low. Who is correct?
O A. Technician A
O B. Neither Technician A nor B
O C. Technician B
O D. Both Technicians A and B

Answers

Answer:

The correct option is;

B. Neither Technician A nor B

Explanation:

A performance test is meant to determine the proper functioning of the air conditioning system for fault finding where repair is required

While the engine is powered off it is expected that to have the same pressure or equal pressures in the low-side and high-side pressure and have a pressure expected for a given ambient temperature, such that, as an example, a system with R134a should have a pressure slightly more than 71 psi. at 70°F

Therefore, neither technicians A nor B is correct as the ambient temperature is important for performance testing and  high-side and low-side pressures should be equal when the engine is powered off.

BHE:FLI:JPM next sequence

Answers

Answer:

NTQ

Explanation:

The given sequence is

BHE : FLI : JPM

If is clear that, alphabets on first places are B, F, J. Difference between their place vales is 4.

B+4=F,F+4=J ; so alphabet on first place of next term of sequence is J+4=N.

Similarly, alphabets on second places are H, L, P. Difference between their place vales is 4.

H+4=L,L+4=P ; so alphabet on second place of next term of sequence is P+4=T.

Alphabets on third places are E, I, M. Difference between their place vales is 4.

E+4=I,I+4=M ; so alphabet on third place of next term of sequence is M+4=Q.

Therefore, the next term is NTQ.

A 30.0 W light bulb in a simple DC circuit is powered by a 9.0 V battery. Assuming there are no other circuit elements, how much current flows through the lightbulb?

Answers

As we know,
[tex]power = (voltage \times current) \\ so \: current = (power \div voltage)[/tex]
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