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 7, Problem 7.45P
A square
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
A 6 kg/s of hot liquid flow continuously without leaking in a 40 mm inside diameter with thickness of 7 mm pipe with temperature of 50℃. Thermal conductivity of pipe is 10W/(m℃) and surface conductance of liquid is 9W/(m^2℃). The outer fluid has temperature of 25℃ and surface conductance of 6W/(m^2℃). Cp of hot liquid = 4.2KJ/(Kg℃). Find the minimum length of pipe in meters just to cool down the hot liquid as much as possible if the maximum heat transfer is the constant heat transfer throughout the pipe.
QUESTION 4
Cold air at 5 °C enters a 12-cm-diameter 20-m-long isothermal pipe at a velocity of 2.5 m/s and leaves
at 19 °C as shown in Figure Q4. Take the pressure of air 1 atm,
i.
estimate the rate of heat transfer to the air, and
ii.
calculate the surface temperature of the pipe.
T,
Air
5°C
12 cm
19°C
2.5 m/s
20 m
Figure Q4
(heat transfer ) thanks
The velocity of the fluid flowing in parallel over a 500mmx500mm flat heater surface is U= 19 m/s and the inlet velocity temperature is T_∞15 C. The surface temperature of this plate is T_s140 C, the friction force is F_D=0.4 N and the surface area of the plate is A=0.32 m2. According to this;(F_D= 0.4N A=32 m2)a) Surface shear stressb) Find the coefficient of frictionc) Heat transfer coefficientd) What is the amount of heat transfer (electric power) that must be given to maintain a constant surface temperature?
Chapter 7 Solutions
Fundamentals of Heat and Mass Transfer
Ch. 7 - Consider the following fluids at a film...Ch. 7 - Engine oil at 100C and a velocity of 0.1 m/s flows...Ch. 7 - Consider steady, parallel flow of atmospheric air...Ch. 7 - Consider a liquid metal (Pr1), with free stream...Ch. 7 - Consider the velocity boundary layer profile for...Ch. 7 - Consider a steady, turbulent boundary layer on and...Ch. 7 - Consider flow over a flat plate for which it is...Ch. 7 - A flat plate of width 1 m is maintained at a...Ch. 7 - An electric air heater consists of a horizontal...Ch. 7 - Consider atmospheric air at 25C and a velocity of...
Ch. 7 - Repeat Problem 7.11 for the case when the boundary...Ch. 7 - Consider water at 27°C in parallel flow over an...Ch. 7 - Explain under what conditions the total rate of...Ch. 7 - In fuel cell stacks, it is desirable to operate...Ch. 7 - The roof of a refrigerated truck compartment is of...Ch. 7 - The top surface of a heated compartment consists...Ch. 7 - Calculate the value of the average heat transfer...Ch. 7 - The proposed design for an anemometer to determine...Ch. 7 - Steel (AISI 1010) plates of thickness =6mm and...Ch. 7 - Consider a rectangular fin that is used to cool a...Ch. 7 - The Weather Channel reports that it is a hot,...Ch. 7 - In the production of sheet metals or plastics, it...Ch. 7 - An array of electronic chips is mounted within a...Ch. 7 - A steel strip emerges from the hot roll section of...Ch. 7 - In Problem 7.23. an anemometer design was...Ch. 7 - One hundred electrical components, each...Ch. 7 - The boundary layer associated with parallel flow...Ch. 7 - Forced air at 250C and 10 m/s is used to cool...Ch. 7 - Air at atmospheric pressure and a temperature of...Ch. 7 - Consider a thin, 50mm50mm fuel cell similar to...Ch. 7 - The cover plate of a flat-plate solar collector is...Ch. 7 - An array of 10 silicon chips, each of length...Ch. 7 - A square (10mm10mm) silicon chip is insulated on...Ch. 7 - A circular pipe of 25-mm outside diameter is...Ch. 7 - An L=1-m- long vertical copper tube of inner...Ch. 7 - A long, cylindrical, electrical heating element of...Ch. 7 - Consider the conditions of Problem 7.49, but now...Ch. 7 - Pin fins are to be specified for use in an...Ch. 7 - Prob. 7.52PCh. 7 - Prob. 7.53PCh. 7 - Hot water at 500C is routed from one building in...Ch. 7 - In a manufacturing process, long aluminum rods of...Ch. 7 - Prob. 7.58PCh. 7 - To determine air velocity changes, it is proposed...Ch. 7 - Determine the convection heat loss from both the...Ch. 7 - Prob. 7.63PCh. 7 - Prob. 7.64PCh. 7 - Prob. 7.67PCh. 7 - A thermocouple is inserted into a hot air duct to...Ch. 7 - Consider a sphere with a diameter of 20 mm and a...Ch. 7 - Prob. 7.76PCh. 7 - A spherical, underwater instrument pod used to...Ch. 7 - Worldwide. over a billion solder balls must be...Ch. 7 - Prob. 7.80PCh. 7 - Prob. 7.81PCh. 7 - Consider the plasma spray coating process of...Ch. 7 - Prob. 7.83PCh. 7 - Tissue engineering involves the development of...Ch. 7 - Consider temperature measurement in a gas stream...Ch. 7 - Prob. 7.89PCh. 7 - A preheater involves the use of condensing steam...Ch. 7 - Prob. 7.91PCh. 7 - A tube bank uses an aligned arrangement of...Ch. 7 - A tube bank uses an aligned arrangement of...Ch. 7 - Repeat Problem 7.94, but with NL=7,NT=10, and...Ch. 7 - Heating and cooling with miniature impinging jets...Ch. 7 - A circular transistor of 10-mm diameter is cooled...Ch. 7 - A long rectangular plate of AISI 304 stainless...Ch. 7 - A cryogenic probe is used to treat cancerous skin...Ch. 7 - Prob. 7.103PCh. 7 - Prob. 7.104PCh. 7 - Prob. 7.105PCh. 7 - Consider the packed bed of aluminum spheres...Ch. 7 - Prob. 7.108PCh. 7 - Prob. 7.109PCh. 7 - Prob. 7.111PCh. 7 - Packed beds of spherical panicles can be sintered...Ch. 7 - Prob. 7.114PCh. 7 - Prob. 7.116PCh. 7 - Prob. 7.117PCh. 7 - Prob. 7.118PCh. 7 - Prob. 7.119PCh. 7 - Prob. 7.120PCh. 7 - Dry air at 35°C and a velocity of 20 m/s flows...Ch. 7 - Prob. 7.123PCh. 7 - Benzene, a known carcinogen, has been spilled on...Ch. 7 - Prob. 7.125PCh. 7 - Prob. 7.126PCh. 7 - Condenser cooling water for a power plant is...Ch. 7 - Prob. 7.128PCh. 7 - In a paper-drying process, the paper moves on a...Ch. 7 - Prob. 7.131PCh. 7 - Prob. 7.132PCh. 7 - Prob. 7.133PCh. 7 - Prob. 7.134PCh. 7 - Prob. 7.136PCh. 7 - It has been suggested that heat transfer from a...Ch. 7 - Prob. 7.138PCh. 7 - Cylindrical dry-bulb and wet-bulb thermometers are...Ch. 7 - The thermal pollution problem is associated with...Ch. 7 - Cranberries are harvested by flooding the bogs in...Ch. 7 - A spherical drop of water, 0.5 mm in diameter, is...Ch. 7 - Prob. 7.143PCh. 7 - Prob. 7.144PCh. 7 - Prob. 7.145PCh. 7 - Prob. 7.146PCh. 7 - Prob. 7.147PCh. 7 - Consider an air-conditioning system composed of a...Ch. 7 - Prob. 7.149P
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
- 30°C, 10m/s 2m Electronic components inside D= 20cm Figure 5 You are designing components of an electronic systems that needs to be inside a 2 m long horizontal duct. The components are sensitive so the cooling mechanism is only done by air flowing over the duct at 30°C and 10 m/s. Initially you proposed a square cross-section with 20-cm length for the duct but is rejected by your client because they said a circular cross- section is better. If the surface temperature of the duct cannot exceed 60°C, find the maximum power rating in kW of the electronics devices that can be located inside the circular cross-section duct. Is it true that circular cross-section is better than a square one for this application?arrow_forwardForced air at T∞ = 25°C and V = 12 m/s is used to cool electronic elements on a circuit board. One such element is a chip, 4 mm × 4 mm, located 153 mm from the leading edge of the board. Experiments have revealed that flow over the board is disturbed by the elements and that convection heat transfer is correlated by an expression of the form Nu_x=0.04Re_x^{0.85}\Pr^{\frac{1}{3}}Nux=0.04Rex0.85Pr31 Estimate the surface temperature of the chip if it is dissipating 32 mW.arrow_forwardAir enters a duct (100 cm *10̟cm*10 cm) at 32°C at a rate of 0.28m /min to cool 138 W electronic component placed on the duct. Assuming 85 percent of the heat generated inside is transferred to air flowing through the duct and the remaining 15 percent is lost through the outer surfaces of the duct. What is the exit temperature of air (°C)? C,= 1007 J/kg.°C, v =1.654×10-S m²/s, p 1.146 kg/m Pr = 0.7268, k = 0.02625 W/m.°C Select one or more:arrow_forward
- For a water flow over a steel surface, the temperature of water at a specific location was found to change with the vertical distance from the surface (y) up to a distance of 0.015 m as T(y) = 60 + 20y + tan(y), where temperature is in °C and y is in cm. The surface temperature and ambient temperature was measured as 60°C and 105°C, respectively. The thermal conductivity of steel and water are, respectively, 48 W/m-K and 0.6 W/m-K. What is the local convection coefficient at this location?arrow_forwardWhat is the value of the heat transfer coefficient for air at 37 ° C flowing at 5 m / s perpendicular to a 10 cm x 10 cm square pipe at 93 ° C? h = 23kcal / hm ^ 2 ° C around this valuearrow_forwardGIVENS: g = 9.8 m/s^2, sin(30°) = 0.50, cos(30°) = 0.87, sin(10°) = 0.17, cos(10°) = 0.98arrow_forward
- The liquid food is flowed through an uninsulated pipe at 90 ° C. The product flow rate is 0.3 kg / s and has a density of 1000 kg / m³, specific heat 4 kJ / (kg K), a viscosity of 8 x 10-6 Pa s, and a thermal conductivity of 0.55 W / (m) K). Assume that the change in viscosity is negligible. The internal diameter of the pipe is 30 mm with a thickness of 3 mm made of stainless steel (k = 15 W / [m ° C]). The outside temperature is 15 ° C. If the outer convective heat transfer coefficient is 18 W / (m² K), calculate the heat loss at steady state per meter pipe length. a. Find the convection coefficient in pipe = W / m² ° C. b. Calculate heat loss per meter pipe length = wattsarrow_forwardThe liquid food is flowed through an uninsulated pipe at 90 ° C. The product flow rate is 0.4 kg / s and has a density of 1000 kg / m³, specific heat 4 kJ / (kg K), a viscosity of 8 x 10-6 Pa s, and a thermal conductivity of 0.55 W / (m) K). Assume that the change in viscosity is negligible. The internal diameter of the pipe is 20 mm with a thickness of 3 mm made of stainless steel (k = 15 W / [m ° C]). The outside temperature is 15 ° C. If the outer convective heat transfer coefficient is 18 W / (m² K), calculate the heat loss at steady state per meter of pipe length. a.Find the convection coefficient in the pipe = AnswerW / m² ° C. b. Calculate heat loss per meter pipe length = Answerwatt.arrow_forwardheat transferarrow_forward
- What is the mass flow rate of air is flowing at a velocity of 20 m/s through a tube with an area of 2 m2 and density of 1.225 kg/m3? Assuming that the airflow is incompressible, what is the new velocity of the mass airflow if the tube narrows to an area of 1 m2? 24.5 kg / s, 10 m/s 49 kg /s, 40 m/s O 12.25 kg / s, 20 m / s 50 slugs / s, 40 ft/sarrow_forwardH.W. Q1: Air enters a 7m long section of a rectangular duct of cross section 15 cm x 20 cm at 50°C at an average velocity of 7 m/s. If the walls of the duct are maintained at 10°C, determine (a) the outlet temperature of the air, (b) the rate of heat transfer from the air. Air properties from tables: p=1.127 kg/m³ C, =1007 J/kg.°C k = 0.02662 W/m.°c Pr = 0.7255 v=1.702×10 m²/s Answer: (a): Te = 34.2 °C, (b): Q' = 3776 W Hint: 1- Use the Logarithmic mean temperature difference relations. 2- If: Reer> 2300, in pipes and ducts, the flow is turbulent. T, = 10°C Air duet 15 cm x 20 cm Air L-7 m 50°C 7 m/sarrow_forwardAn ideal gas passes a diffuser. At the diffuser inlet, the temperature is T1 = 350.00 K, the pressure P1 = 100.00 kPa, the velocity V1 = 200.00 m/s, and the inlet area A1 = 0.30 m2. At the exit, the velocity is very small. The specific heat of the ideal gas at the constant pressure is cp = 1.0050 kJ/(kg·K). The gas constant is R = 0.2870 kPa·m3/(kg·K). Determine the enthalpy per unit mass at the inlet, h1__________(kJ/kg)arrow_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