What is the difference between natural and forced convection?
The key difference between natural and forced convection is that in natural convection, the motion of the fluid is influenced by natural means whereas, in forced convection, the motion of fluids is influenced by external means.
What is meant by natural convection?
Natural convection is a type of flow, of motion of a liquid such as water or a gas such as air, in which the fluid motion is not generated by any external source (like a pump, fan, suction device, etc.) but by some parts of the fluid being heavier than other parts. The driving force for natural convection is gravity.
Why it is called as natural convection?
Fig. 1: Natural convection heat transfer from a hot body. The temperature of the air adjacent to the hot object is higher, thus its density is lower. As a result, the heated air rises. This movement is called the natural convection current.
What causes natural convection?
Natural convection arises from temperature differences among air parcels, or heat transfer at surfaces (i.e. surface-to-air temperature difference). In the absence of forced convection, natural convection becomes the only means of air mixing inside enclosed spaces.
What is the greatest disadvantage of natural convection?
Advantage of natural convection is, it doesn’t require any additional cost for heat transfer. While it’s disadvantage is, it is ineffective in static systems for heat transfer.
Under which condition the natural convection is not possible?
R: Natural convection is not possible in gravity free space.
What are the advantages and disadvantages of a convection oven?
What are the Pros and Cons of a Convection Oven?
- #1 They Cook Food Evenly.
- #2 The Cooking Time Is Shorter.
- #3 You Can Cook More Than One Dish at a Time.
- #4 You Can Put the Dishes Anywhere.
- #1 You Have to Adjust Recipes.
- #2 Your Dough Won’t Rise.
- #3 They Are More Fragile.
- #4 Too Many Dishes Can Hinder the Performance.
Which statement is true of natural convection?
1. Which of the following is true about Natural Convection? Explanation: Natural Convection has low heat transfer. It is due to gravity and natural buoyant forces and is dependent on viscosity, density and thermal conductivity.
How do you find natural convection?
Natural convection coefficient calculator
- Plane area A= m2
- Plane perimeter P= m.
- Plane height L= m.
- Angle from vertical °
- Diameter D= m.
- Density ρ = kg/m3 Viscosity μ = N*s/m2 Specific heat C = J/kg*K. Thermal conductivity k = W/m*K. Thermal expansion coefficient β = 1/K.
What causes free convection?
Free convection refers to fluid motion induced by buoyancy forces. Buoyancy forces may arise in a fluid for which there are density gradients and a body force that is proportional to density. In heat transfer, density gradients are due to temperature gradients and the body force is gravitational.
In which two phases of matter can convection currents occur?
Unlike the other two, convection can only happen in fluids. This includes liquids and gases and is because the molecules have to be free to move. Heat energy can transfer by convection when there is a significant difference in temperature between two parts of a fluid.