/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q66P Evaporative cooling of beverages... [FREE SOLUTION] | 91影视

91影视

Evaporative cooling of beverages. A cold beverage can be kept cold even on a warm day if it is slipped into a porous ceramic container that has been soaked in water. Assume that energy lost to evaporation matches the net energy gained via the radiation exchange through the top and side surfaces. The container and beverage have temperature T=15掳颁, the environment has temperature Tenv=32掳颁 , and the container is a cylinder with radius r=2.2cm and height 10cm . Approximate the emissivity as=1, and neglect other energy exchanges. At what rate is the container losing water mass?

Short Answer

Expert verified

The rateat which the container loses water mass is6.8107kg/s

Step by step solution

01

Identification of given data

i) The temperature of the container with the beverage is T=15Cor288K

ii) The temperature of the environment is Tenv=32Cor305K

iii) The radius of the cylinder is r=2.2cmor0.022m

iv) The height of the cylinder is h=10cmor0.10m

v) The emissivity of the material, =1

02

Significance of evaporation and thermal radiation

The process of evaporation occurs on the surface of the liquid as it changes from the present liquid state to the gaseous state. Here, a certain amount of heat is released by the body during the phase change process that is radiated as the amount of thermal energy by the system. Thermal radiation is the amount of electromagnetic radiation emitted from a material that is due to the heat radiated by the material depending on its temperature. Thus, the energy lost due to evaporation is equal to the energy gained due to radiation.

Formulae:

The conduction rate at which heat energy is transferred by a body,

Pcond=kA(THTC)L 鈥(颈)

where,kis the thermal conductivity of the material,Ais the surface area of radiation,THis the temperature at the hotter end,TLis the temperature at the colder end,Lis the length of the conduction.

The heat energy released by the body, Q=Lvm 鈥(颈颈)

Where, Lfis the latent heat of fusion, m is the mass of the substance.

The rate of radiation by a body, Prad=A(Tenv4T4) 鈥(颈颈颈)

Where,is the Stefan鈥揃oltzmann constant and is equal to(5.67108W/m2.K4),is the emissivity of the substance,Ais the surface of the area of radiation,Tenvis the temperature of the environment,Tis the thermodynamic temperature.

03

Determining the rate at which the container losses water

Energy is lost by the beverage due to evaporation. Then, the heat of vaporization is given by using equation (ii), where

The heat of vaporization,LV=2.256106J/kg

Differentiating equation (ii) with respect to time, we get the rate as:

dQdt=LVdmdt 鈥(颈惫)

The energy lost due to evaporation equals the energy gained by radiation. Hence, equating equation (iv) with equation (iii), we get that

LVdmdt=A(Tenv4T4) 鈥(惫)

The total surface area of the container (a cylinder with one end open) is given as:

A=r2+2rh=3.14(0.022m)2+23.140.022m0.10m=1.53102m2

Substituting the given values and the above area, equation (v) gives the rate of mass loss as:

dmdt=A(Tenv4T4)LV=5.67108W/m2.K41.01.53102m2((305K)4(288K)4)2.256106J/kg=6.8107kg/s

Hence, the required value of the mass loss by the container is 6.8107kg/s

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Samples A and B are at different initial temperatures when they are placed in a thermally insulated container and allowed to come to thermal equilibrium. Figure a gives their temperatures T versus time t. Sample A has a mass of5.0kg; sample B has a mass of 1.5kg. Figure b is a general plot for the material of sample B. It shows the temperature change Tthat the material undergoes when energy is transferred to it as heat Q. The changeTis plotted versus the energy Q per unit mass of the material, and the scale of the vertical axis is set by Ts=4.00C.What is the specific heat of sample A?

A thermodynamic system is taken from state A to state B to state C, and then back to A, as shown in the p-V diagram of Figure a. The vertical scale is set by ps=40 Pa, and the horizontal scale is set by Vs=4.0 m3. (a) Complete the table in Figure b by inserting a plus sign, a minus sign, or a zero in each indicated cell. (h) What is the net work done by the system as it moves once through the cycle ABCA?

A steel rod is 3.00 cmin diameter at25.00oC. A brass ring has an interior diameter of 2.992 cm at25.00oC. At what common temperature will the ring just slide onto the rod?

A 150 gcopper bowl contains 220 gof water, both at20.0C. A very hot 300 gcopper cylinder is dropped into the water, causing the water to boil, with 5.00 g being converted to steam. The final temperature of the system is100C. Neglect energy transfers with the environment. (a) How much energy (in calories) is transferred to the water as heat? (b) How much to the bowl? (c) What is the original temperature of the cylinder?

An athlete needs to lose weight and decides to do it by 鈥減umping iron.鈥 (a) How many times must a 80.0kgweight be lifted a distance of 1.00min order to burn off 1.00lbof fat, assuming that that much fat is equivalent to 3500Cal?(b) If the weight is lifted once every2.00s, how long does the task take?

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.