1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Stella [2.4K]
3 years ago
10

Under conditions for which the same roojm temperature is mainteined bt a heating or cooling system, it is not uncommon for a per

son to feel chilled in the winter but comfortable in the summer. Provide a plausible explanation for this situation (with supporting calculations) y by considering a room whose air temperature is maintained at 20 Dagree C throughout the year, while the walls of the room are nominally at 27 Dagree C and 14 Dagree C in the summer and winter, respectively. The exposed surface of a person in the room may be assumed to be at a temperature of 32 Dagree C throughout the year and to have an emissivity of 0.90. The coefficient associated with heat transfer by natural convection between the person and the room air is approximately 2 W/m2 Middot K.
Engineering
1 answer:
bonufazy [111]3 years ago
7 0

Answer:

Net heat transfers:  during summer = 52.253 W/m^2 during winter = 119.375 w/m^2

Explanation:

Given data :

Room temperature throughout the year = 20⁰c = 293 k

Room temperature during summer = 27⁰c = 300 k

Room temperature during winter = 14⁰c = 287 k

surface temperature of a person throughout the year = 32⁰c = 305 k

coefficient of heat transfer by natural convection (h)= 2 w /m^2 k

emissivity = 0.9

An explanation to the condition of feeling chilled during the winter and comfortable during summer  can be explained with the calculation below

The heat transfer from the surface body of a person the the room is carried out by convection and this can be calculated as

q = hΔt = 2 * ( 305  -  293) = 2 * 12 = 24 w /m^2

also calculate heat transfer through radiation using this formula

q_{rad} = εσ [ (Temperature of body)^4- (temperature of room at each season)^4 ]

ε = 0.90,(emissivity)    σ = 5.67 *10^-8 w/^2 . k ( Boltzmann's constant)

during summer :

q_{rad} = (0.90)*(5.67*10^-8)* ( 305^4 - 300^4 ) = 28.253 W/m^2

therefore the net heat transfer during the summer = 24 w/m^3 + 28.253 W/m^3 = 52.253 W/m^2

During winter :

q_{rad} = (0.90)*(5.67*10^-8) * ( 305^4 - 287^4 ) = 95.375 W/m^3

therefore the net heat transfer during the winter

= 24 w/m^3 + 95.375w/m^3 = 119.375 w/m^2

You might be interested in
A 50-lbm iron casting, initially at 700o F, is quenched in a tank filled with 2121 lbm of oil, initially at 80o F. The iron cast
insens350 [35]

Answer:

a) The final equilibrium temperature is 83.23°F

b) The entropy production within the system is 1.9 Btu/°R

Explanation:

See attached workings

8 0
3 years ago
Information or signals entered into a computer system is
Virty [35]

<em>Logs.</em>

<em>Like data logs. Sometimes people make these logs to keep tabs on other people or to get important information put down somewhere that way it is saved and can be looked back upon later. Anytime someone makes an action on the computer, it makes a TMP file representing a log of what you want it to do before the computer quickly get's rid of the file.</em>

<em>-Ɽ3₮Ɽ0 Ⱬ3Ɽ0</em>

<em />

8 0
2 years ago
A formal indication from a state, on letterhead, or an official state form, that shows the applicant has valid driving privilege
alex41 [277]

A formal indication from a state, on letterhead, or an official state form, which shows that an applicant has valid driving privileges and is clear to apply for a Colorado driver's license is called a clearance.

<h3>What is a learner's license?</h3>

A learner's license is also referred to as learner's permit and it can be defined as a category of driver's license that is issued to an individual who is learning how to drive an automobile vehicle (car).

<h3>What is a license?</h3>

A license is also referred to as a certificate and it can be defined as an authorization that is typically issued by state governments to a driver, so as to avail him or her the legal ability to physically driver in all the states across a country.

In this scenario, we can infer and logically deduce that a clearance is a formal indication from a state which shows and affirms that an applicant has valid driving privileges, and is permitted to apply for a Colorado driver's license.

Learn more about learner's license here: brainly.com/question/26289148

#SPJ1

7 0
1 year ago
A square silicon chip (k = 152 W/m·K) is of width 7 mm on a side and of thickness 3 mm. The chip is mounted in a substrate such
Harrizon [31]

Answer:

The steady-state temperature difference is 2.42 K

Explanation:

Rate of heat transfer = kA∆T/t

Rate of heat transfer = 6 W

k is the heat transfer coefficient = 152 W/m.K

A is the area of the square silicon = width^2 = (7/1000)^2 = 4.9×10^-5 m^2

t is the thickness of the silicon = 3 mm = 3/1000 = 0.003 m

6 = 152×4.9×10^-5×∆T/0.003

∆T = 6×0.003/152×4.9×10^-5 = 2.42 K

7 0
3 years ago
Uestion 10
Dimas [21]
Tryna boost my score for college stuff could you give me the brainiest and a thanks? Hope you find your answer your looking for!
6 0
3 years ago
Other questions:
  • What is the energy change when the temperature of 15.0 grams of solid silver is decreased from 37.3 °C to 20.5 °C ?
    13·1 answer
  • A turbojet aircraft flies with a velocity of 800 ft/s at an altitude where the air is at 10 psia and 20 F. The compressor has a
    8·2 answers
  • Tranquilizing drugs that inhibit sympathetic nervous system activity often effectively reduce people's subjective experience of
    8·1 answer
  • Consider the following incomplete code segment, which is intended to print the sum of the digits in num. For example, when num i
    8·1 answer
  • A 0.50 m3 drum was filled with 0.49 m3 of liquid water at 25oC and the remaining volume was water vapor without any air. The dru
    15·1 answer
  • Today I meant to look for my missing watch, but I could never find the time.
    9·2 answers
  • I’m doing a project on renewable energy. There are 6 energy sources. Solar, wind, geothermal, hydroelectric, tidal, and biomass.
    14·2 answers
  • A misfire code is a type ____ DTC<br> A) 1 or 2<br> B) a or b<br> C) c or d<br> D l or ll
    15·1 answer
  • An ideal vapor-compression refrigeration cycle using refrigerant-134a as the working fluid is used to cool a brine solution to −
    12·1 answer
  • Determine the maximum height (in inches) that a lift pump can raise water (0.9971 g/ml) from a well at normal atmospheric pressu
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!