Videos
What is natural convection? How does it differ from forced convection? What force causes natural convection currents?
The meaning of natural convection, the difference between the natural and forced convections and the force causing natural convection currents.
Explanation of Solution
Introduction:
There are three modes of heat transfer:
- Conduction
- Convection
- Radiation
The convection heat transfer is associated to heat transfer in fluids (liquid and gases) in which there is physical movement of fluid particles. On the basis offorce responsible for the physical movement of fluid particles, the convection is classified as natural and forced convection.
Natural Convection: The convection heat transfer process in which the bulk movement of fluid particles is observed due to density variations arising out of temperature difference is called the natural convection. The difference in temperature causes variation in different fluid layers, and this density variation facilitates movement of fluid particles without any aid of external force. There is no external force involved for the fluid motion.That is why it is referred as natural convection.
Forced Convection: When the movement of fluid particles is assisted by some external media such as fan, blower, pump, suction device, the heat transfer occurring in fluid is termed as forced convection. The forced convection results in better mixing and hence is faster and more efficient. The mild forces like buoyancy and gravity do not play any role in forced convection and the heat transfer process is dominated by the external force.
Forced convection caused by fan
The main difference between the natural and forced convection is the presence of external force. If the external force is present in heat transfer process, it is termed as forced convection, otherwise the convection heat transfer process is natural convection.
The force which play role in natural convection are buoyancy and gravity. The gravity becomes dominant in liquids which helps in producing the natural currents of heat transfer. The heated particles become less dense, they tend to move upward, and cold heavy particles move downward due to gravity, resulting in formation of natural currents. These natural currents are responsible for natural convection.
Want to see more full solutions like this?
Chapter 9 Solutions
HEAT+MASS TRANSFER:FUND.+APPL.
Additional Engineering Textbook Solutions
Starting Out with Python (4th Edition)
Experiencing MIS
SURVEY OF OPERATING SYSTEMS
Thermodynamics: An Engineering Approach
Automotive Technology: Principles, Diagnosis, And Service (6th Edition) (halderman Automotive Series)
Vector Mechanics for Engineers: Statics and Dynamics
- handwritten-solutions, please!arrow_forwardhandwritten-solutions, please!arrow_forwardRequired information An eccentric force P is applied as shown to a steel bar of 25 × 90-mm cross section. The strains at A and B have been measured and found to be εΑ = +490 μ εB=-70 μ Know that E = 200 GPa. 25 mm 30 mm 90 mm 45 mm B Determine the distance d. The distance dis 15 mm mm.arrow_forward
- handwritten-solutions, please!arrow_forwardhandwritten-solutions, please!arrow_forward! Required information Assume that the couple shown acts in a vertical plane. Take M = 25 kip.in. r = 0.75 in. A B 4.8 in. M 1.2 in. [1.2 in. Determine the stress at point B. The stress at point B is ksi.arrow_forward
- Problem 6 (Optional, extra 6 points) 150 mm 150 mm 120 mm 80 mm 60 mm PROBLEM 18.103 A 2.5 kg homogeneous disk of radius 80 mm rotates with an angular velocity ₁ with respect to arm ABC, which is welded to a shaft DCE rotating as shown at the constant rate w212 rad/s. Friction in the bearing at A causes ₁ to decrease at the rate of 15 rad/s². Determine the dynamic reactions at D and E at a time when ₁ has decreased to 50 rad/s. Answer: 5=-22.01 +26.8} N E=-21.2-5.20Ĵ Narrow_forwardProblem 1. Two uniform rods AB and CE, each of weight 3 lb and length 2 ft, are welded to each other at their midpoints. Knowing that this assembly has an angular velocity of constant magnitude c = 12 rad/s, determine: (1). the magnitude and direction of the angular momentum HD of the assembly about D. (2). the dynamic reactions (ignore mg) at the bearings at A and B. 9 in. 3 in. 03 9 in. 3 in. Answers: HD = 0.162 i +0.184 j slug-ft²/s HG = 2.21 k Ay =-1.1 lb; Az = 0; By = 1.1 lb; B₂ = 0.arrow_forwardProblem 5 (Optional, extra 6 points) A 6-lb homogeneous disk of radius 3 in. spins as shown at the constant rate w₁ = 60 rad/s. The disk is supported by the fork-ended rod AB, which is welded to the vertical shaft CBD. The system is at rest when a couple Mo= (0.25ft-lb)j is applied to the shaft for 2 s and then removed. Determine the dynamic reactions at C and D before and after the couple has been removed at 2 s. 4 in. C B Mo 5 in 4 in. Note: 2 rotating around CD induced by Mo is NOT constant before Mo is removed. and ₂ (two unknowns) are related by the equation: ₂ =0+ w₂t 3 in. Partial Answer (after Mo has been removed): C-7.81+7.43k lb D -7.81 7.43 lbarrow_forward
Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University Press
Mechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSON
Thermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEY
Mechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage Learning
Engineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY