Fundamentals of Heat and Mass Transfer
7th Edition
ISBN: 9780470917855
Author: Bergman, Theodore L./
Publisher: John Wiley & Sons Inc
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 4, Problem 4.15P
A small water droplet of diameter
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Problem 3
The air above the surface of a freshwater lake is at temperature TA
while the water is at its freezing point T,(T,< T,). After a time t
elapsed, ice of thickness y has formed. Ássuming that the heat,
which is liberated when the water freezes, flows through the ice by
conduction and then into the air by natural convection, prove
y
T, – T,
pl
h 2K
where h is the convection coefficient per unit area and is assumed
constant while ice forms, K is the thermal conductivity of ice, I is the
latent heat of fusion of ice, and p is the density of ice (Hint: the
temperature of the upper surface is variable. Ássume that the ice
has a thickness y and imagine an infinitesimal thickness dy to form
in time dt.)
A group of students were tasked to compare the coefficient of performance of the freezer
after observing how effective it operates after it converts a certain amount of water to ice in 6
hours. They were able to construct the table shown below. Compute the actual and ideal
COP for both freezers
Panasonic
White
Westinghouse
0.08 hp
Power rating
42 W
Mass of water
15 kg
20.5 kg
Latent heat of solidification
80 cal/g
80 cal/g
Interior temperature
Exterior temperature
0.9-
- 10°C
31'C
20°C
THERMODYNAMICS
A 1.5kW iron has a 0.5 cm thick brass base plate (p=8,310 kg/m3 and cp = 400 J/kg C) with a surface area of 0.03 m^2. At the start, the iron is in thermal equilibrium with the ambient air temperature of 22 degrees Celsius. What is the shortest time required for the plate temperature to reach 200 degrees Celsius if 95 percent of the heat generated in the resistance wires is transmitted to the plate?
Chapter 4 Solutions
Fundamentals of Heat and Mass Transfer
Ch. 4 - In the method of separation of variables (Section...Ch. 4 - A two-dimensional rectangular plate is subjected...Ch. 4 - Consider the two-dimensional rectangular plate of...Ch. 4 - A two-dimensional rectangular plate is subjected...Ch. 4 - A two-dimensional rectangular plate is subjected...Ch. 4 - Using the thermal resistance relations developed...Ch. 4 - Free convection heat transfer is sometimes...Ch. 4 - Consider Problem 4.5 for the case where the plate...Ch. 4 - Prob. 4.9PCh. 4 - Based on the dimensionless conduction heat rates...
Ch. 4 - Determine the heat transfer rate between two...Ch. 4 - A two-dimensional object is subjected to...Ch. 4 - An electrical heater 100 mm long and 5 mm in...Ch. 4 - Two parallel pipelines spaced 0.5 m apart are...Ch. 4 - A small water droplet of diameter D=100m and...Ch. 4 - A tube of diameter 50 mm having a surface...Ch. 4 - Pressurized steam at 450K flows through a long,...Ch. 4 - The temperature distribution in laser-irradiated...Ch. 4 - Hot water at 85°C flows through a thin-walled...Ch. 4 - A furnace of cubical shape, with external...Ch. 4 - Laser beams are used to thermally process...Ch. 4 - A double-glazed window consists of two sheets of...Ch. 4 - A pipeline, used for the transport of crude oil,...Ch. 4 - A long power transmission cable is buried at a...Ch. 4 - A small device is used to measure the surface...Ch. 4 - A cubical glass melting furnace has exterior...Ch. 4 - An aluminum heat sink (k=240W/mK), used to cool an...Ch. 4 - Hot water is transported from a cogeneration power...Ch. 4 - A long constantan wire of 1-mm diameter is butt...Ch. 4 - A hole of diameter D=0.25m is drilled through the...Ch. 4 - In Chapter 3 we that, whenever fins are attached...Ch. 4 - An igloo is built in the shape of a hemisphere,...Ch. 4 - Prob. 4.34PCh. 4 - An electronic device, in the form of a disk 20 mm...Ch. 4 - The elemental unit of an air heater consists of a...Ch. 4 - Prob. 4.37PCh. 4 - Prob. 4.38PCh. 4 - Prob. 4.39PCh. 4 - Prob. 4.40PCh. 4 - One of the strengths of numerical methods is their...Ch. 4 - Determine expressionsfor...Ch. 4 - Consider heat transfer in a one-dimensional...Ch. 4 - In a two-dimensional cylindrical configuration,...Ch. 4 - Upper and lower surfaces of a bus bar are...Ch. 4 - Derive the nodal finite-difference equations for...Ch. 4 - Consider the nodal point 0 located on the boundary...Ch. 4 - Prob. 4.48PCh. 4 - Prob. 4.49PCh. 4 - Consider the network for a two-dimensional system...Ch. 4 - An ancient myth describes how a wooden ship was...Ch. 4 - Consider the square channel shown in the sketch...Ch. 4 - A long conducting rod of rectangular cross section...Ch. 4 - A flue passing hot exhaust gases has a square...Ch. 4 - Steady-state temperatures (K) at three nodal...Ch. 4 - Functionally graded materials are intentionally...Ch. 4 - Steady-state temperatures at selected nodal points...Ch. 4 - Consider an aluminum heat sink (k=240W/mK), such...Ch. 4 - Conduction within relatively complex geometries...Ch. 4 - Prob. 4.60PCh. 4 - The steady-state temperatures (°C) associated with...Ch. 4 - A steady-state, finite-difference analysis has...Ch. 4 - Prob. 4.63PCh. 4 - Prob. 4.64PCh. 4 - Consider a two-dimensional. straight triangular...Ch. 4 - A common arrangement for heating a large surface...Ch. 4 - A long, solid cylinder of diameter D=25mm is...Ch. 4 - Consider Problem 4.69. An engineer desires to...Ch. 4 - Prob. 4.71PCh. 4 - Prob. 4.72PCh. 4 - Prob. 4.73PCh. 4 - Refer to the two-dimensional rectangular plate of...Ch. 4 - The shape factor for conduction through the edge...Ch. 4 - Prob. 4.77PCh. 4 - A simplified representation for cooling in very...Ch. 4 - Prob. 4.84PCh. 4 - A long trapezoidal bar is subjected to uniform...Ch. 4 - Consider the system of Problem 4.54. The interior...Ch. 4 - A long furnace. constructed from refractory brick...Ch. 4 - A hot pipe is embedded eccentrically as shown in a...Ch. 4 - A hot liquid flows along a V-groove in a solid...Ch. 4 - Prob. 4S.5PCh. 4 - Hollow prismatic bars fabricated from plain carbon...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- find the driving pressure for a stack that has a height of 18 m and carry a hot gas mixture with an average density of 1.2 k/m3. If you know that the total heat rejection by the stack is 1450 KJ and the c, of the hot gas is 1.8 KJ/Kg.K while the hot gas inlet and outlet temperature are 650 K and 500 K respectively. Assume the hot gas pressure as 2.3 bar while the ambient pressure is 1 bar.arrow_forwarda tray of liquid water is placed in a freezer where it cools from 20 deg C to "-5" deg C. what is the total amount of energy needed to freeze per unit of liquid water? the specific heat of ice is half of the specific heat of liquid water. the latent heat of fusion for water is 335 kj/kg include diagramarrow_forwardSuppose that as a body cools, the temperature of the surrounding medium increases because it completely absorbs the heat being lost by the body. Let T(t) and Tm (t) be the temperatures of the body and the medium at time t, respectively. If the initial temperature of the body is T1 and the initial temperature of the medium is T2, then it can be shown in this case that Newton's law of cooling is dT/dt = k(T - Tm ), k 0 is a constant. (a) The foregoing DE is autonomous. Determine the limiting value of the temperature T(t) as t→ o What is the limiting value of Tm (t) as t→o? (b) Verify your answers in part (a) by actually solving the differential equation. (c) Discuss a physical interpretation of your answers in part (a).arrow_forward
- 2. Calculate the mass of silver initially at 445 °C which would be needed to be dropped into a 435 mL sample of water initially at 23.0 °C in an insulated container to raise the temperature of the water to 33.5 °C. The specific heat capacity of water is 4.184 J K-¹ g¹ and the molar heat capacity of silver is 25.9 J K¹ mol¹¹. 2 Tot 21arrow_forwardPlease provide Handwritten answerarrow_forwardA steel ball with a diameter of 10 mm is taken suddenly from a medium at a temperature of 25ºc and annealed for 20 minutes in the furnace host at a temperature of 800ºc. How many ° C is the temperature of the steel ball when it comes out of the oven? (ρ(steel) = 7854 kg / m3, C(steel) = 434 J / kgK, h(air) = 10 W / m2K and h(oil) =100 W / m2K) a. 705.65 b. 662.90 c. 706.25 d. 750.81 e. 750.20arrow_forward
- Question 5: Z=62 a. An iron sphere of mass (Z + 300)g is kept in a container having boiling water (100 °C). If the temperature of the sphere is 25.5°C, how much heat energy is absorbed by the iron sphere? Consider the specific heat of iron as 452J/kg. b. The wall of an industrial furnace is constructed from (Z + 3) cm thick fireclay brick having a thermal conductivity of 1.7 W/mK. Measurements made during steady-state operation reveal temperatures of 530°C and 375°C at the inner and outer surfaces, respectively. Find the rate of heat loss through a wall which is (Z + 5) cm by (Z + 3) m on a side.arrow_forwardNumber 4 A food product wants to be produced in a small round shape (pellet) by freezing it in a water blast freezer freezer. Air freezer operates at a temperature of -35 ° C. The initial product temperature is 25 ° C. The pellet has a diameter of 1.2 cm, and a density of 980 kg / m³. The initial freezing temperature is -2.5 ° C. The latent heat of freezing of the product is 280 kJ / kg. The thermal conductivity of the frozen product is 1.9 W / (m ° C). The convective heat transfer coefficient is 50 W / (m² K). Calculate the freeze time. identify : a. tf = Answer in hourarrow_forwardA glass vessel with an insulating cover with a surface area of (Z + 100) cm² and (Z + 15) mm thick is filled with ice at 0° C and placed in a second vessel maintained at a temperature of 100° C. Find the mass of the ice that melts per minute when the flow of heat becomes steady. Latent heat of ice = 3.3 x 105 J/kg and K for glass = 1.0 W /mK. %3!arrow_forward
- An ice chest is constructed of Styrofoam [k=0.033 W/(m.k)] with inside dimension of 25 by 40 by 100 cm. The wall thickness is 5.0 cm. The outside of the chest is exposed to air at 25 oC with h=10 W/m2oC. If the chest is completely filled with ice, calculate the time for the ice to completely melt. State your assumptions. The heat of fusion is 330 KJ/kg. Heat transfer through the wall joints maybe neglected.arrow_forwardSolving Thermal Properties Related Problems Estimate the thermal diffusivity of butter at 20°C.arrow_forwardanswer provided is correctarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
Principles of Heat Transfer (Activate Learning wi...
Mechanical Engineering
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Cengage Learning
Heat Transfer – Conduction, Convection and Radiation; Author: NG Science;https://www.youtube.com/watch?v=Me60Ti0E_rY;License: Standard youtube license