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The Optimal Specifications for a Heat Exchanger from the Guidance of the Quran Dr. Zaid Kasim Mohammad Ghazzawi Website:

Introduction: Heat exchangers are devices which exchange thermal energy between two fluids. The design of such devices is a major specialization in the field of mechanical engineering and there is a continuous research to know the optimal specification for such devices, because such specifications ensure the exchange of heat with minimum cost and time. We see Muslims running to the stranger from religion to learn these sciences and pay a large amount of money in the process, while Allah (God) as it will be shown in this article teaches the believer all branches of knowledge in details from the last revelation of Allah (God) to people (i.e. The Quran). Thus if a person wants to learn the optimal design specifications for a heat exchanger he needs to ask Allah (God) this knowledge. This article shows how to learn such knowledge from the Quran. The Methodology of Learning Engineering Sciences from The Quran: If we ponder upon the statement of Allah (God) in The Quran in verse 21 of chapter 51 (And in your ownselves will you not then see), we find that Allah (God) Almighty urges us to ponder upon the creation of our bodies, knowing that our body contains all engineering systems such as thermal, structural, chemical, electromagnetic, etc. And if we link this with verse 4 of chapter 95 which states (Allah (God) created humans in an optimal form), we can learn that Allah (God) created our bodies in an optimal form, meaning that it has optimal specifications for all its engineering systems and this is called in engineering sciences (Optimal Engineering). Thus to learn the optimal specifications for any engineering system we need to think about the engineering systems found in the human body and in this article I will


concentrate on finding the optimal specifications for a heat exchanger. Thus the question now is: where is the heat exchanger in our body? If we think about the skin in our body we find that it is the main place where thermal energy is exchanged between the inner environment of the body and the external one as shown in figure 1. The mercy requires that there is fast exchange of heat between our body and the external environment such that there is no accumulation of heat within the body and thus no pain nor fatigue. And as such we can learn the optimal specifications for a heat exchanger by pondering upon how Allah (God) designed our skin since He did that in an optimal fashion.

.Figure 1: The design of Allah (God) for human skin

Thus we can learn the optimal specifications for a heat exchanger by pondering upon how Allah (God) designed the human skin, as follows: 1. The outer surface of human skin: We notice from pondering upon the outer surface of human skin that Allah (God) created this surface having a wavy shape like water waves as shown in figure 2.


.Figure 2: The wavy outer surface for human skin

This wavy shape yields a large surface area for the skin for thermal exchange to occur at between the inner environment of the human skin, which has a higher temperature compared to the outer environment. Thus we can learn that Allah (God) teaches us that in order to have a large exchange of thermal energy we need to increase the area of the surface dividing the two fluids involved in the exchange of thermal energy.

2. Skin thickness: If we think about the thickness of human skin we find that Allah (God) designed the skin to have a very small thickness. Thus we learn that we need to minimize the thickness of human skin to maximize heat transfer as shown in figure 3.


Figure 3: Reduction of skin thermal resistance by the reduction of skin thickness.

3. Skin Morphology: We find upon pondering upon human skin that Allah (God) designed it to have a smooth shape which does not contain any sharp edges as shown in figure 4. This design from an engineering point of view ensures that no locations have high concentration of heat and thus no pain. Thus we learn here that we need to avoid making any sharp edges in the design of heat exchangers to avoid having hot spots, because such spots cause a large increase in the temperature which can cause damage in the material from which the exchanger is composed of.


Figure 4: The smooth design for human skin.

4. Objects on skin’s surface: Looking at the outer surface of the skin we find it full of hairs. Thus the question arises as to what is the function of hairs from an engineering point of view? To know the answer to this question we need to a comparison between two surfaces; one containing no hairs on its surface and the other containing hairs on its surface. Assuming that air flows on these two surfaces, and if we look first at the surface containing no hairs we see the results as shown in figure 5.


.Figure 5: Accumulation of air atoms on a surface without hairs

We notice that the bare surface cause air atoms to accumulate on it which causes a layer called the boundary layer to form, which in turn reduces the transfer of thermal energy from and to the surface. Since heat needs to be transported from one layer of atoms to another for exchange to take place. If we compare this case to the case where the surface contains hairs on it as shown in figure 6.


Figure 6: Hairs causing turbulence of air atoms near to skin surface.

We find from the results that when hairs are placed on the surface it breaks the accumulation of air atoms (i.e. the boundary layer), which enhances the exchange of thermal energy, since the atom which harnessed heat leaves its place quickly and a colder atom comes to take its place. Thus we notice that placing hairs on the skin surface causes turbulence in the air adjacent to the surface. If we link all of this with what Allah (God) states in verse 8 of chapter 35 of the Quran (And Allah (God) who sends the winds so that they cause turbulence in the clouds and Allah (God) drives it to a dead land and gives life by it to a land after its death and as such will be the resurrection). Thus we learn that Allah (God) teaches us that the formation of clouds which involves mass and heat transfer is accomplished by causing turbulence in the matter involved in the process. Thus we learn that the state of turbulence is the optimal state for mass and heat exchange. And so we learn that in order to enhance the process of the exchange of thermal energy we need to cause turbulence in the fluids involved in the process and this can be accomplished by placing objects on the surface separating the two fluids.

An Example: I will show now how to apply part of the knowledge learned from the Quran in the design of a heat exchanger by using finite element analysis (FEA), such that figure 7 shows a surface for a heat exchanger having a wavy surface like that of water waves similar to the human skin.


Figure 7: A surface for a heat exchanger having a wavy surface.

Figure 8 shows the heat flux obtained from such a surface under certain boundary conditions. It has been obtained that the maximum value of thermal flux is equal to 47 W/m2.

Figure 8: Heat flux from a heat exchanger having a wavy surface.

If we compare this design which is developed from the guidance of Allah (God) in the Quran with a flat surface as shown in figures 9 and 10.


Figure 9: A flat surface for a heat exchanger.

Figure 10: Heat flux from a heat exchanger having a flat surface.

We find that the maximum value of the thermal flux in the case of a flat surface is equal to 37 W/m2. Thus we see that thermal flux increased by 20 % when the surface of the exchanger is wavy. We notice brothers and sisters the knowledge that can be obtained by pondering upon the verses of the Quran, and we realize that the current status of Muslims as being humiliated receivers of other is due to the fact that they abandoned Allah (God) and His


book and this is in perfect agreement with the statement of Allah (God) in the Quran in verse 30 of chapter 25 (And the messenger said O my Lord my nation abandoned this Quran).

Dr. Zaid Kasim Mohammad Ghazzawi Website:


The Design of a Heat Exchanger from The Quran