Recently, the usage of Nanofluids has been increased drastically. If you are pursuing your Ph.D. in Nanofluids, this article will help you in getting the basic knowledge on Nanofluids. A few numbers of MCQ Questions along with Short Questions on Nanofluids are described here with very simple language.
Further, if you want to get the PDF format of this sheet, please click on the PDF downloadable button located at the end of this article.
Now, let’s start with the MCQ Questions or Objective Questions on Nanofluids.
MCQ Questions on Nanofluids
- The solid particles of nanofluid are
- Both ✔
- The term “Nano-fluid” was first discovered by
- S.U.S Choi, Zhang,Lockwood,Grulke
- S.U.S Choi ✔
- Hyun UK Kang, Sung Hyun Kang
- Samy Joseph Becaye, Cong Tam Palm
- None of these
- The term “Nano-fluid” was first discovered in
- 1995 ✔
- The size of the particles in Nano-fluid is
- Greater than 100nm
- Equal to 100 nm
- Less than 100 nm ✔
- None of these
- The purpose of using Nano-fluid is
- To reduce thermal conductivity
- To enhance the heat transfer ✔
- None of these
- Which one of the following is true?
- The thermal conductivity of base fluid is less than that of the fluid when nano-particle is mixed with it. ✔
- The thermal conductivity of base fluid is more than that of the fluid when nano-particle is mixed with it.
- One nanometer is equal to __meter
- 10^-9 ✔
- None of these
Short Questions on Nanofluids
What is nanofluid?
Ans: When the diameter of the particles in a fluid is less than 100nm, the fluid is termed a nanofluid. You can disperse nano-particles of metals/non-metals like copper, aluminum, alumina, or metallic oxides like zinc oxide, aluminum oxide, etc in a conventional liquid such as water, ethylene glycol, etc. Then, you will get the nanofluid.
What is nanotechnology?
Ans: The technology that is conducted at nano-scale. It means that the dimensions of the particles involved in this technology must be less than 100 nm.
Why the nanofluids are used?
Ans: The thermal conductivity of a nanofluid is higher than that of a normal fluid. Nanofluids are used to increase heat transfer. It can enhance heat transfer because of its enhanced thermal properties.
What do you mean by nanofluid stability?
Ans: If the particle reacts with the fluid within which the particles are suspended, the nanofluid is said as chemically unstable.
If the suspended particles agglomerate, then the nanofluid is said to be unstable.
What is surfactant in a nanofluid?
Ans: For enhancing the stability of the nanofluid, surfactants are used. It helps in reducing the surface tension between two substances. These are the surface-active agents. Depending on the composition and polarity, surfactants are of four types: anionic, cationic, non-ionic, amphoteric. Soap and detergents act as surfactants. These molecules help us in washing properly.
What are the advantages of surfactants used in nanofluids?
Ans: Surfactants reduce the surface tension between two substances. As a result, the nanoparticles can’t agglomerate. Agglomeration of nanoparticles reduces heat transfer.
What are the disadvantages of surfactants used in nanofluids?
Ans: Adding a large number of surfactants with the nanofluid increases the slight density and viscosity of the nanofluid. Also, it reduces the thermal conductivity a little bit.
How many different ways you can produce nanofluids?
Ans: Nanofluids are prepared using the following techniques:
- One step method
- Direct evaporation method
- Chemical vapour condensation method
- Chemical precipitation method
- Two step method
- Gas condensation or dispersion method
- Bio-based method
What do you mean by One step method and Two step method?
Ans: There are mainly two ways to prepare the nanofluids: The one Step Method and the Two-step Method.
In the one-step method, making the nanoparticles and dispersing those into the base fluid are performed simultaneously. This helps in reducing the agglomeration. As a result, it increases the stability of the nanofluid. Nanofluids in mass-scale can’t be produced by using this method. Also, the cost will be very high. There are many advanced ways to synthesize nanofluids to avoid these issues, such as the one-step chemical method.
By opting for chemical or physical methods, nanoparticles are first converted into dry powders. This is the first step. In the next step, these Nano-sized powder is dispersed into the base fluid with the help of magnetic force, ultrasonic agitation, or high shear mixing force. For producing the Nanofluids on a large scale, this method is used. But, in this method, there are more chances of the Nanoparticles to agglomerate. To avoid this problem, the right amount of surfactants at the right temperature should be used.
What do you mean by stability of a nanofluid?
Ans: The purpose of using Nanofluid is to enhance the thermal conductivity of the fluid. When some Nano-particles are dispersed into a base fluid like water or oil, the thermal conductivity of water increases. But if the Nanoparticles can’t stay in a suspended position and sediments at the bottom of agglomerates, the Nanofluid can’t enhance the thermal conductivity. So, the purpose of using the Nanofluid is lost. Therefore, the stability of a Nanofluid is of big concern.
What are the ways to reduce the sedimentation?
Ans: One of the best ways to reduce sedimentation is to use the right amount of surfactants.
Name some nanofluids and indicate their composition.
Ans: Water with copper Nanoparticles: The volume fraction of Nanoparticles is 0.3 to 2%.
Gold in water: Gold Nanoparticles are suspended in de-ionized water.
Silver in water: Here also, the base fluid is de-ionized water.
There are many Nanofluids where the Nanoparticles are of metal- oxides, such as Al2O3-water, CuO-water, AgO-water, etc.
Indicate some applications of nanofluids?
Ans: The devices where the heat transfer rate is of main concern such as heat exchangers, electronic cooling systems, air conditioning, and refrigeration system Nanofluids are used.
What is hybrid Nanofluid?
Ans: When two different types of Nanoparticles are dispersed into the base fluid, it is called Hybrid Nanofluid. It is observed that the thermal conductivity of Hybrid Nanofluid is more than that of Nanofluids.
I hope, this article-“Short Questions on Nanofluids” will help you and also will encourage you in proceeding further in your research. Also, it will help you in many different competitive examinations. If you want articles on some other topics, please don’t forget to write the same in the comment box.