Question

During the experiment of shell and tube heat exchanger by using this equipment the Source of the water was from the water tap that is mean it is open feed water

To explain more:    the lab engineer used a drink water that supply it from the water tap directly to the heat exchanger equipment

And then he discharge the water to the sink that is not correct way ? I do not have a scientific answer in this but what i think the water from tap is not laminer and the temperature

is not fixed . so I need a real explanation in mechanical and chemical engineering about this

CAN you explain why the way of supplying water like this to the equipment is not good ?

and what the engineer used ?

which type of liquid shall he used ? And why and how it will improve

think about salt in the normal water as well as the bacteria, Think about fouling factor , cleaning heat exchanger regularly,

Answer 1

First let me explain the fact Mechanically

If we use the tap water the following consequences may occur

1.The designed flow and pressure may not be supplied to the heat exchanger.As they are designed to operate for certain pressure and flow rates.If the requirements doesnot reached ,the effectiveness of the heat exchanger is unutilised.

2.the heat exchanger are designed to operate under turbulent flow conditions because in turbulent flow the boundary layers of waters which are formed on the wall tube are broken and results in well mixing of the bulk fluid. In case of laminar flow the boundary layers being formed will reduce the rate of heat transfer.

And also the temparature of the fluid also should not be varied which inturn results in change of viscosity which causes losses as well as change in flow conditions.

Now comes to the chemical point of view .

If we use the tap water the following consequences may occur

1 .corrossion of the pipes will occur. which leads to scale formation

2 . the presence of salts will depositte on the tube walls (fouling).which reduces the water flow and heat transfer rate.

3.the presence of bacteria will lead to algea formation.

Following are the requirements of water for the heat exchanger

1.the water quality is measured in terms of contaminents parts per million (ppm).The water ppm must maintained within 4-10 ppm in order have a good working conditions. The water of this value ppm is called A grade water or soft water.soft water is produced by softening plant by removing the salts present in it.

2.In order to maintain the piping system in good condition one must use a chemical dozing system.which mainly contains the chemicals like corrossion inhibitor, flucculent, Anti-scalant, Antioxidant, Membrane cleaners etc.....

3 .the filters are must equipped in any kind of hydraulic and pneumatic systems.Because any contaminents present in the fluid must be removed before entering the system.Filters must replaced or cleaned when they are choked.

4 .the cleaning of the heat exchanger some times is needed.Because if the contaminents enter the system will choke the entire system.The daily cleaning of heat exchanger is not needed when you use proper filter and good quality water.