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
Studentka2010 [4]
3 years ago
13

Thermal energy storage systems commonly involve a packed bed of solid spheres, through which a hot gas flows if the system is be

ing charged, or a cold gas if it is being discharged. In a charging process, heat transfer from the hot gas increases thermal energy stored within the colder spheres; during discharge, the stored energy decreases as heat is transferred from the warmer spheres to the cooler gas.
Engineering
1 answer:
zheka24 [161]3 years ago
4 0

Answer:

as the exercise is incomplete, I add the information that is missing:

Consider a packed bed of 75-mm-diameter aluminum spheres ? = 2700 kg/m3, and c = 950 J/kg

Answer: The copper can store 34.1% more thermal energy at 272.42ºC

Explanation:

Given:

Diameter packed bed = 75 mm

Density = 2700 kg/m³

specific heat = 950 J/kg K

initial temperature sphere = 25ºC

thermal conductivity = 240 W/m K

temperature of gas = 300ºC

convection coefficient = 75 W/m²K

The characteristic length is

L_{c} =\frac{r}{3} =\frac{0.0375}{3} =0.0125m

The Biot number is equal to

Bi=\frac{hL_{c} }{k} =\frac{75*0.0125}{240} =3.9x10^{-6}

Bi < 1, we will use the lumped capacitance method

The energy transfer is equal to:

\frac{Q}{Q_{max} } =(1-exp(\frac{t}{t_{t} } )) (eq. 1)

t_{t} =\frac{pV}{hA} =\frac{p\frac{\pi D^{3} }{6} c}{h\pi D^{2} } =\frac{pDc}{6h} \\t_{t}=\frac{2700*0.075*950}{6*75} =427.5s

Replacing in eq. 1

0.9=1-exp(\frac{-t}{t_{t} } )\\0.1=exp(\frac{-t}{t_{t} } )\\\frac{-t}{t_{t} } =ln(0.1)\\t=2.3t_{t}=2.3*427.5=983.25s

The temperature at the center of sphere is

T=T\alpha +(T_{i} -T\alpha )exp(\frac{-6ht}{pDc} )=300+(25-300)exp(\frac{-6*75*983.25}{2700*0.075*950} )=272.42C

We obtain the percentage increase

Cpcu = 385 J/kg K

(pCp)cu = 8933 * 385 = 3439205 J/m³K

from water:

(pCp)wa = 2700 * 950 = 2565000 J/m³K

the percentage increase is

%P = (3439205 - 2565000)/2565000 = 34.1%

The copper can store 34.1% more thermal energy.

You might be interested in
Transcription machinery assembles at _______________.
vivado [14]

Answer:

The base

Explanation:

3 0
3 years ago
A hydraulic cylinder is to be used to move a workpiece in a manufacturing operation through a distance of 50 mm in 10 s. A force
svetlana [45]

Answer:

The answer to this question is 1273885.3 ∅

Explanation:

<em>The first step is to determine the required  hydraulic flow rate liquid if working pressure and  if a cylinder with a piston diameter of 100 mm is available.</em>

<em>Given that,</em>

<em>The distance = 50mm</em>

<em>The time t =10 seconds</em>

<em>The force F = 10kN</em>

<em>The piston diameter is = 100mm</em>

<em>The pressure = F/A</em>

<em> 10 * 10^3/Δ/Δ </em>

<em> P = 1273885.3503 pa</em>

<em>Then</em>

<em>Power = work/time  = Force * distance /time</em>

<em> = 10 * 1000 * 0.050/10</em>

<em>which is  =50 watt</em>

<em>Power =∅ΔP</em>

<em>50 = 1273885.3 ∅</em>

5 0
3 years ago
PLS HELP ME
Oksana_A [137]

Answer:

The Euler buckling load of a 160-cm-long column will be 1.33 times the Euler buckling load of an equivalent 120-cm-long column.

Explanation:

160 - 120 = 40

120 = 100

40 = X

40 x 100 / 120 = X

4000 / 120 = X

33.333 = X

120 = 100

160 = X

160 x 100 /120 = X

16000 / 120 = X

133.333 = X

4 0
3 years ago
Two vehicles arrive at an uncontrolled intersection from different streets at the same time 1.The driver on the right must yield
ss7ja [257]
3. Both vehicles must stop
4 0
3 years ago
When the psychologist simply records the relationship between two variables...
Wewaii [24]
When a psychologist simply records the relationship between two variables without manipulating them, it is called a correlational study.

The observed relationship does not by itself reveal which variable causes the other. This is the directionally problem. Also, the relationship may be due to a third variable controlling both of the observed variables.
8 0
3 years ago
Other questions:
  • Convert 0.025 in into mm.
    11·2 answers
  • What is the name of the model/shape below?
    5·2 answers
  • Your new mobile phone business is now approaching its first anniversary and you are able to step back and finally take a deep br
    8·1 answer
  • The Emergency Stop Button icon on the Inputs toolbar can be used to press or release the Emergency Stop button on the CNC machin
    10·1 answer
  • Write a single statement that prints outsideTemperature with 2 digits in the fraction
    8·1 answer
  • What fraction of the worlds surface is estimated to be arable land?
    15·1 answer
  • A geothermal heat pump absorbs 15 KJ/s of heat from the Earth 15 m below a house. This heat pump uses a 7.45 kJ/s compressor.
    14·2 answers
  • A. Derive linear density expressions for BCC [110] and [111] directions in terms of the atomic radius R.
    7·1 answer
  • Parting tool purpose
    13·1 answer
  • A system samples a sinusoid of frequency 230 Hz at a rate of 175 Hz and writes the sampled signal to its output without further
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!