# Force Convection

In: Science

Submitted By noormi
Words 945
Pages 4
Title: Forced Convection
Objective:
To demonstrate the use of extended surface such as fin and pin to improve the heat transfer in forced convection.
Introduction:
Convection is the study of conduction in a fluid as enhanced by its "convective transport", that is, its velocity with respect to a solid surface. It thus combines the energy equation, or first law of thermodynamics, with the continuity and momentum relations of fluid mechanics. The causes of convection are generally described as one of either natural or forced. However the distinction between natural and forced convection is particularly important for convective heat transfer.
Forced convection or also known as heat advection studies the heat transfer between a moving fluid and a solid surface. There are various types of forced convection, such as flow in a tube or across a flat plate and so on. In forced convection, the fluid has a nonzero streaming motion in the field away from the body surface, caused perhaps by a pump or fan or other driving force independent of the presence of the body. Also in this class are bodies moving through a still fluid, since fluid velocities are forced and may be large, heat transfer via forced convection will usually be significantly larger. It should be considered as one of the main methods of useful heat transfer as significant amounts of heat energy can be transported very efficiently and this mechanism is found very commonly in everyday life, including central heating, air conditioning, steam turbines and in many other machines. Convection is also used in engineering practices to provide desired temperature changes, as in heating of homes, industrial processes, cooling of equipment, etc.

Theoretical background: Convection is one of the major modes of heat transfer and mass transfer. Convective heat and mass transfer take place through individual particles...

### Similar Documents

Free Essay

#### Force Convection

...turbine efficiency when the brake force is increase Theoretical Background: Radial flow When a fluid flows radially inwards or outwards from a centre, between two parallel planes as in Fig. 6.21, the streamlines will be radial straight lines and the streamtubes will be in forms of sectors. The area of flow will therefore increase as the radius increases, causing the velocity to decrease. Since the flow pattern is symmetrical, the total energy per unit weight H will be the same for all streamlines and for all points along each streamlines if we assume that there is no loss of energy. [pic] Figure 6.21 If v is the radial velocity and p is the pressure at any radius r, H = p/ρg + v²/2g = constant …………………………(6.31) Applying the continuity of flow equation flow and assuming that the density of the fluid remains constant, as would be the case for the fluid, Volume rate of flow, Q = area x velocity = 2πrb x v where b is the distance between the planes. Thus, v = Q/2πrb and substituting in equation………(6.31) p/ρg + Q²/ 8π²r²b² = H p = ρg [ H – ( Q²/ 8π²b² ) x ( 1/r² )] …………………..(6.32) If the pressure p at any radius r is plotted in Fig. 6.21(c), the curve will be parabolic and is sometimes referred to as Barlow’s curve. If the flow discharges to the atmosphere at the periphery, the pressure at any points between the plates will be below atmospheric; there will be a force tending to bring the two plates......

Words: 1571 - Pages: 7

#### Heat Transfer

...Conduction is most prevalent in solids but it can also be found in liquids and gases. The rate at which heat is transmitted through a material by conduction depends on thermal conductivity which is a characteristic of a material and its mass. The easiest way to think of conduction is to hold a metal rod by one end and put the other over a fire. Eventually the hot energetic molecules from the fire will transfer to the cold, less energetic molecules of the metal rod and slowly creep up the rod to the cold end where it is being held and then move to the hand and cause burns. The second method of heat transfer is convection which is the transfer of energy through a circulating gas or liquid to or from a solid object. An example of convection is a pot on the hot stove to the water inside which then heats up the pot and the that heats up the water. Convection consists of two energy transfer mechanisms. The first occurs...

Words: 568 - Pages: 3

#### Heat Transfer and Its Applications

...transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species, either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system. Heat conduction, also called diffusion, is the direct microscopic exchange of kinetic energy of particles through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described by the second law of thermodynamics. Heat convection occurs when bulk flow of a fluid (gas or liquid) carries heat along with the flow of matter in the fluid. The flow of fluid may be forced by external processes, or sometimes (in gravitational fields) by buoyancy forces caused when thermal energy expands the fluid (for example in a fire plume), thus influencing its own transfer. The latter process is often called "natural convection". All convective processes also move heat partly by diffusion, as well. Another form of convection is forced convection. In this case the fluid is forced to flow by use of a pump, fan or......

Words: 312 - Pages: 2

#### Convction

...THERMODYNAMICS Page 1 of 2 TD1005 Free and Forced Convection Shows free and forced convection from different heat transfer surfaces Works with Typical screenshot of the VDAS® software • Self-contained, bench-top mounting • Includes three of the most common heat transfer surfaces – flat plate, pinned and finned • Simple and safe to use • Thermocouples and a sensitive anemometer measure temperatures and air velocity – shown on a digital display • Additional hand-held thermocouple probe included – to measure temperatures along the length of the pins and fins of two heat transfer surfaces • Variable speed fan and variable power heat source for a range of tests • Can connect to TecQuipment’s Versatile Data Acquisition System (VDAS®) • • • • TecQuipment Ltd, Bonsall Street, Long Eaton, Nottingham NG10 2AN, UK T +44 115 972 2611 • F +44 115 973 1520 • E info@tecquipment.com • W www.tecquipment.com An ISO 9001 certified company VDAS is a registered trademark of TecQuipment Ltd DB/0411 Page 2 of 2 TD1005 Free and Forced Convection Description Experiments The bench-mounting equipment includes a vertical duct that holds the chosen heat transfer surface and all instruments needed. • Comparing free and forced convection for different surfaces TecQuipment include three different common heat transfer surfaces with the equipment: • A Flat Plate • Comparison of free convection from vertical and horizontal (finned)......

Words: 744 - Pages: 3

#### Refrigeration

...Initial Evaporative Comparison of R-22 with Alternative Refrigerants R-134a and R-321R-125 J. P. Wattelet, J. C. Chato, A. L. Souza, and B. R. Christoffersen ACRCTR-39 June 1993 For additional information: Air Conditioning and Refrigeration Center University of Illinois Mechanical & Industrial Engineering Dept. 1206 West Green Street Urbana, IL 61801 (217) 333-3115 Prepared as part ofACRC Project 01 Refrigerant-Side Evaporation and Condensation Studies 1. C. Chato, Principal Investigator The Air Conditioning and Refrigeration Center was founded in 1988 with a grant from the estate of Richard W. Kritzer, the founder of Peerless of America Inc. A State of Illinois Technology Challenge Grant helped build the laboratory facilities. The ACRC receives continuing support from the Richard W. Kritzer Endowment and the National Science Foundation. Thefollowing organizations have also become sponsors of the Center. Acustar Division of Chrysler Allied-Signal, Inc. Amana Refrigeration, Inc. Brazeway, Inc. Carrier Corporation Caterpillar, Inc. E. I. du Pont de Nemours & Co. Electric Power Research Institute Ford Motor Company Frigidaire Company General Electric Company Harrison Division of GM ICI Americas, Inc. Modine Manufacturing Co. Peerless of America, Inc. Environmental Protection Agency U. S. Army CERL Whirlpool Corporation For additional iriformation: Air Conditioning & Refrigeration Center Mechanical & Industrial Engineering Dept. University of Illinois 1206 West......

Words: 1491 - Pages: 6

#### Lab Report

...Introduction For the purpose of studying combined radiation and free convection heat transfer, this experiment measured the surface temperature of two aluminum flat plates during heat-up. Both plates' lower surfaces were well insulated. For comparison, one plate was considered to be ideal blackbody, which is a perfect absorber and emits; the other one was polished, yielding different radiant properties. According to the procedure, both plates were heated under the lamp from room temperature; plates' temperature was measured with a thermocouple and recorded with LabView Program. To analyze the results, appropriate assumptions were made and correct conservations of energy were chosen. Results and Discussion Based on the data collected in the experiment, Temperature vs Time were plotted for both plates, as shown in figure 1 and figure 3. Our plates were exposed under the lamp for a longer time than claimed in the procedure to reach a relatively steady state, because the lamp we were using was weaker than normal ones. Figure 1, Temperature vs Time for Blackbody Plate Energy terms in the energy balance equation were also calculated and plotted as shown in figure 3 and figure 4. Equations that used to do all the calculations can be found in Appendix A and Appendix B. All the calculations were done using Microsoft Excel. Figure 2, Energy terms vs Time for Blackbody Plate Irradiation, Gtot was calculated to be 1456.95 W/m2. Since the initial temperature of plate......

Words: 402 - Pages: 2

#### Tutorial 2 Engineering

...(1) (Welty, Rorrer, Foster, 6th Edition International Student Version 16.2) It is desired to transport liquid metal through a pipe embedded in a wall at a point where the temperature is 650K. A 1.2-m thick wall constructed of a material having thermal conductivity varying with temperature according to , where T is in K and k is in W/m.K, has its inside surface maintained at 925 K. The outside surface is exposed to air at 300 K with a convective heat transfer coefficient of 23 W/m2.K. How far from the hot surface should the pipe be located. What is the heat flux for the wall? (2) WWWR 17.13 A 2.5-cm-thick sheet of plastic (k = 2.42 W/m.K) is to be bonded to a 5-cm-thick aluminium plate. The glue that will accomplish the bonding is to be held at a temperature of 325K to achieve the best adherence, and the heat to accomplish this temperature is to be provided by a radiant source. The convective heat transfer coefficient on the surfaces of both the plastic and aluminium is 12 W/m2.K, and the surrounding air is at 295 K. What is the required heat flux if it is applied to the surface of (a) plastic? (b) aluminium? (3) (Modified from Welty, Rorrer, Foster, 6th Edition International Student Version 16.1) The steady state expression for heat conduction through a plane wall is . For steady state heat conduction through a hollow cylinder, an expression similar to the equation is Where is the log-mean are defined as a. Show that as defined above satisfies the equations for...

Words: 1263 - Pages: 6

Free Essay

#### Observations to the Characteristics of Diffusion

...Observations on the Characteristics of Diffusion A Scientific Paper Submitted to Professor Christina Barazona College of Science and Mathematics - Department of Biological Sciences Mindanao State University – Iligan Institute of Technology Andres Bonifacio Avenue, Tibanga, 9200 Iligan City, Philippines By Janna R. Andalan August 2013 ABSTRACT The Experiment conducted involves diffusion. The point of this experiment was to know the characteristics of diffusion and to formulate hypothesis based on diffusion. It has also a purpose to see whether the diffusion is dependent on distance, rate and molecular weight of the substance. The estimation of distance is predicted by getting the average of the substance. Rate is predicted by subtracting the final diameter to initial diameter and dividing it by time. It is determined that there are three things which influence the movement of molecules such as kinetic energy, nature of the environment and size of the molecules. By this, we know which dye diffused at the fastest rate by measuring the diameter of the colored area immediately after adding the substance to the agar plate. After one hour of measuring the methylene blue by 15 minutes interval, the substance moved immediately in 0min until 45minutes, the remaining minutes remains the same. While on the potassium permanganate, the substance moved from 0minutes to 1hour. These happened because they had different molecular weight and also the size of the......

Words: 1685 - Pages: 7

...Table of Contents Abstract 2 Introduction 2 The Fire Problem 2 Methodology 5 Results and discussion 6 Processes of flame spread 7 Diffusion flame spread 8 Thermal Model 8 Transition to Turbulence 10 References 13 Abstract The fires problem is one of the hazard pose a threat to life and property. Flames behave differently under various conditions which include: the oxygen available, combustible material, orientation of surfaces, etc. this a complex phenomena which is influenced by multiple factors that includes ignition, heat release rate, flame spread and the generation of different products of combustion like carbon IV oxide and carbon II oxide. The research was performed by studying various sources in the library and in the internet and also performing experiments to simulate a real life situation. Introduction The Fire Problem The flammability of a material is a complex event which is influenced by multiple factors that includes ignition, heat release rate, flame spread and the generation of different products of combustion like carbon IV oxide and carbon II oxide. In order to better protect the people and property from risk posed by the unwanted fires, it become necessary to understands all these factors under different conditions. Babrauskas and Vytenis 1992 suggested that heat release rate is the main variable in fire hazard; but Kashiwagi and Ito argued effectively that, the flame spread over the......

Words: 2735 - Pages: 11

Free Essay

#### Design of a Finned Radiator Assembly

...MAE 441 | Design of a Finned Radiator Assembly | Heat Exchanger Design Project | Thien Van TranChris LongfieldEric PacewiczOlivia Ching | | 4/3/2012 | | Scope of the Project The objective of the project was to design an effective radiator assembly to accommodate the Diesel-Engine Generator Set 1500-XC6DT2 by incorporating the use of tubes with inner fins in various geometries in order to meet the heat rejection requirements specified. This was done with consideration for minimizing cost, size, and complexity. Initial Parameters The initial parameters were the operating requirements of the Diesel-Engine Generator Set 1500-XC6DT2 are as follows: * Coolant capacity – The coolant chosen for our radiator is ethylene glycol (50/50 % by volume) * Its maximum operating temperature of 225F * Air flow rate – Since the generator is stationary as opposed to that used in an automobile application, a fan will be needed to provide the necessary flow rate. The required air flow rate specified by the engine is 9.383 m3/s in order to dissipate the heat generated * Coolant flow rate – The coolant flow rate is 17.914 kg/s through the radiator * The initial coolant temperature is assumed to be 212F, which is slightly below the operating temperature of the engine. The initial coolant temperature is taken as the ethylene glycol entering the radiator immediately after leaving the engine. * Pressure drop allowance – The * The total heat......

Words: 1400 - Pages: 6

Free Essay

#### Mkt1

...Company G 3-Year Marketing Plan Assessment Code: Mkt1 Student Name: Rhonda Wilson Student ID: 000165977 Date: May 25, 2009 Mentor Name: Khirstin Hadley Table of Contents Introduction Error! Bookmark not defined. Mission Statement Error! Bookmark not defined. Market Objectives Error! Bookmark not defined. Target Market Error! Bookmark not defined. Product Objective Error! Bookmark not defined. Price Objective Error! Bookmark not defined. Place Objective Error! Bookmark not defined. Promotion Objective Error! Bookmark not defined. Competitive Situation Analysis Error! Bookmark not defined. Consumer Product Classification Error! Bookmark not defined. Analysis of Competition using Porter’s 5 Forces Model Error! Bookmark not defined. SWOT Analysis Error! Bookmark not defined. Strengths Error! Bookmark not defined. Weaknesses Error! Bookmark not defined. Opportunities Error! Bookmark not defined. Threats Error! Bookmark not defined. Marketing Strategies Error! Bookmark not defined. Product Strategies Error! Bookmark not defined. Price Strategies Error! Bookmark not defined. Place Strategies Error! Bookmark not defined. Promotion Strategies Error! Bookmark not defined. Tactics and Action Plan Error! Bookmark not defined. Product Action Plan 7 Price Action Plan 7 Place Action Plan 7 Promotion Action Plan 7 Monitoring Procedures Error! Bookmark not defined. Mission Statement: Our mission is to provide top......

Words: 2001 - Pages: 9

Free Essay

#### Marketing Plan

...Error! Bookmark not defined. Consumer Product Classification Error! Bookmark not defined. Analysis of Competition using Porter’s 5 Forces Model Error! Bookmark not defined. SWOT Analysis Error! Bookmark not defined. Strengths Error! Bookmark not defined. Weaknesses Error! Bookmark not defined. Opportunities Error! Bookmark not defined. Threats Error! Bookmark not defined. Marketing Strategies Error! Bookmark not defined. Product Strategies Error! Bookmark not defined. Price Strategies Error! Bookmark not defined. Place Strategies Error! Bookmark not defined. Promotion Strategies Error! Bookmark not defined. Tactics and Action Plan Error! Bookmark not defined. Product Action Plan 7 Price Action Plan 7 Place Action Plan 7 Promotion Action Plan 7 Monitoring Procedures Error! Bookmark not defined. Mission Statement: Our mission is to provide top quality appliances that will become the global brand of choice. Company G was established by top designers and engineers who are continuously innovating new appliances to keep up with our evolving market. Market Objectives: Target Market: We want to provide an oven that heats food just as fast as a microwave but provides tastier and healthier foods for our everyday families. We want to focus on working class families with children that want to provide healthier meals. Our convection oven will...

Words: 1986 - Pages: 8

Free Essay

#### Market Share

...Market Share 1. Air Conditioners Market Share The India air conditioner market in 2011 was estimated at 3.14 million units. According to latest data from market researcher GfK-Nielsen India, LG's volume market share in multi-brand outlets-a key sales channel that accounts for almost 90% of AC dealerships-stood at 17.7% in May 2012 against 18.3% of Voltas. Samsung retained its third slot in room ACs but its market share has plunged from 14.5% in July 2011 to 10% in May 2012. The drop was a result of it vacating the window AC segment this year; now it is not far behind Japanese brand Panasonic, which has doubled market share to 9.9% in the last 10 months. Even Hitachi increased its market share from 5.2% to 7.3% in the period. Players Brand | Company | Onida | Mirc electronics Limited | Videocon | Videocon International Limited | LG | LG Electronics India Limited | Samsung | Samsung India Electronics Limited | Whirlpool | Whirlpool of India Limited | Godrej | Godrej and Boyce Mfg. Co. Limited | Voltas | Voltas Limited | Electrolux | Electrolux Kelvinator | Blue Star | Blue Star India Limited | Daikin | Daikin Industries Limited | Past Market Share Name of the Company | 2002-03 | 2005-06 | 2007-08 | Blue Star | 14.53 | 16.51 | 17.98 | Voltas | 12.12 | 11.95 | 14.11 | L G Electronics India Pvt. | 13.54 | 18.85 | 13.2 | Samsung India Electronics Pvt. | 3.93 | 7.01 | 6.88 | 2. Washing Machine The Indian washing machine market......

Words: 1049 - Pages: 5

Free Essay

#### Catering Equipment Specialists Since 1983

...bbq items, glassware and blenders. A large range of top brands such as Kenwood, Dualit, Buffalo, KitchenAid, Vogue, Panasonic, Werzalit, Samsung and Churchill are stocked. These are all priced extremely competitively, but there are also budget options. All products sold are selected for quality and performance. The catering clothing range offers mens, womens and unisex designs. All the leading ranges of chefs knives from brands including Global, Victorinox, Wusthof, Dick and many more are sold. The knives are of exceptional quality and are great value investments. We also stock high quality budget options for those working to a stricter budget. There are many different commercial ovens available including electric and gas ovens, convection ovens, combination ovens, ranges and pizza ovens. We also sell many other catering appliances for a wide variety of purposes including induction hobs, gas rings, fryers, grills, griddles, rice cookers and gas hobs. We are proud of our next day delivery, which has been the heart of our success for almost 30 years. Our commitment to both quality products and excellent service, means our customers come back year after...

Words: 282 - Pages: 2

Free Essay