Friday, January 26, 2018

solar energy utilization

Innovative idea
Ingenious design of a device for the industrial effluent treatment with solar energy
There are many popular methods for purifying waste water from industries and salt water from sea by using solar energy. In general all these processes are based on boiling the contaminated water to produce steam and condensing the steam with cool surface. It is not only the oldest but also most effective, since it removes bacteria far below the acceptable level, but it is inefficient in eliminating the chemical toxins there in particularly with low boiling point. However complete sterilization of water is not required. Solutes not dissolved in water , contaminates of high boiling point will remain in the boiling water itself. In general  99.9 % pure water can be obtained by distillation.
Solar disinfection is a low-cost method of disinfecting water that can often be implemented with locally available cheap materials. No complicated technical knowledge is required so that  it can be well used by all kind of people even uneducated. One of the major advantages of this method is it has low impact on the environment. It does not require any fire-wood or electricity for heating and it is well suitable to all countries where solar flux is available  almost through the year. It helps to solve the problem of energy crisis by saving the energy used for water purification and water crisis by distributing drinking water to all.
An ingenious device for the industrial effluent treatment with solar energy is designed. It is based on the vaporization at reduced pressure.  The rate of vapourization can be increased  without heating by  reducing the pressure lower than the normal atmospheric pressure. This is because lower the applied pressure , lower will be the boiling point. The normal boiling point of pure water is 1000C at NTP. Its boiling point decrease exponentially with the reduction in the applied pressure. When the applied pressure is reduced by half water boils at 810C and at one fourth of the atmospheric pressure it is 520C. Since the distillation is carried out at lower temperature, it is suitable only for effluent with contaminate of high boiling point.
It works under the same principle as that of the 20 lts mineral water can used for tapping drinking water in homes. It has two cans instead of one and are connected together with a slantwise bent tube made up of glass. Initially the bent tube is completely filled with pure water and kept inverted by holding water inside. It is carefully placed such that one end of which is kept immersed in the wider metallic vessel containing salt  or contaminated water while the other end of the tube is kept immersed  in the pure water taken in a glass jar with an outlet. The narrow neck will not allow fast drainage of water and a column of water will stand in both the limbs of the bent tube. A pressure lower than the atmospheric pressure is developed in the bent tube above the water level. It promotes the process of vaporization. The  as the boiling point is lowered due to low pressure..The wider bottom of the tube  helps the heated water to flow into the bend glass tube effectively. The metallic vessel is properly housed in a flat plate collector exclusively designed for it so that solar heat collected is transferred to water by conduction Care must be taken to reduce the energy loss by convection and radiation from the system. The outer surface at the bottom of metallic vessel is also blackened to absorb the solar flux directly to improve its efficiency. With the help of a reservoir with an outlet  attached with the metallic vessel waste water is fed  to the system for continuous working. This system is best useful for waste water having contaminates of high boiling point. During continuous usage   residue will be deposited at the bottom of the vessel which must be removed then and there, otherwise the heat conduction from the flat plate collector will be reduced gradually.

Dr.M.Meyappan is a retired professor of Physics worked in Alagappa Government Arts College, Karaikudi, Tamilnadu. 

Sunday, January 7, 2018

short story

ஆன்மீகச் சிறு கதை
கடவுளைக் கண்டேன்                                                                                                                        "கடவுள் இருக்கின்றாரா "                                                                                                              "இருக்கின்றார்"                                                                                                                                  " எங்கே இருக்கின்றார் ?"
"எங்கும் இருக்கின்றார் "
" அப்படியென்றால் கடவுள் ஏன் ஒருவர் கண்களுக்கும் தென்படவில்லை ?"
"எல்லோருக்கும் தென்படவேண்டும் என்பதற்காக ஒருவருக்கும் தென்படவில்லை "
"புரியவில்லை. இன்னும் கொஞ்சம் விளக்கமாகக் கூறமுடியுமா ?
மின் விசிறியைச் சுட்டிக்காட்டி  " இந்த மின் விசிறியில் எத்துணை இறக்கைகள் இருக்கின்றன ?"
"மூன்று "
"உனக்குத் தெரிகின்றதா ? "
"தெரிகின்றது "
மின் விசிறியை ஓட விட்டுவிட்டு  " இப்பொழுது அந்த விசிறிகள் தெரிகின்றதா ?
"தெரியவில்லை '
"ஏன் ? "
"அவை எங்கும் சுற்றிக் கொண்டிருப்பதால்  கண்களால் பார்க்கமுடியவில்லை ஆனால் தெரிந்து கொள்ள முடிகின்றது "
" சரியாகச் சொன்னாய் .. கடவுள் உனக்கும் எனக்கும் மட்டுமல்ல . எல்லோருக்கும் பொதுவானவர். மின் விசிறி போல உலகைச் சுற்றி ஓயாது வளம் வரும் கடவுளைக் காணமுடியாது , உணரத்தான் முடியும் "
 கடவுளைக் கண்டு விட்ட மகிழ்ச்சியால்  மனம் ஆனந்தக் கூத்தாடியது.