IIT Kharagpur Lessons

I am not the student of the IIT Kharagpur. I am doing the B.Tech Electrical Engineering from the Sangam University. It will good form me if I can read the content of the IIT Kharagpur. Please give me the IIT Kharagpur video lessons for the Electrical Engineering?

I want the notes of Lesson 1 Refrigeration and Air Conditioning of NTPEL of IIT Kharagpur so can you provide me?

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National Programme on Technology Enhanced Learning NPTEL is an initiative by seven Indian Institutes of Technology (IIT Bombay, Delhi, Guwahati, Kanpur, Kharagpur, Madras and Roorkee) and Indian Institute of Science (IISc) for creating course contents in engineering and science.

NPTEL provides E-learning through online Web and Video courses various streams.

IIT Kharagpur NPTEL Lesson 1 Refrigeration and Air Conditioning

History Of Refrigeration

Objectives of the lesson:

The objectives of this lesson are to:

1. Define refrigeration and air conditioning (Section 1.1)

2. Introduce aspects of various natural refrigeration methods, namely:
a. Use of ice transported from colder regions (Section 1.2)
b. Use of ice harvested in winter and stored in ice houses (Section 1.2)
c. Use of ice produced by nocturnal cooling (Section 1.2.1)
d. Use of evaporative cooling (Section 1.2.2)
e. Cooling by salt solutions (Section 1.2.3)

3. Introduce historical aspects of various artificial refrigeration methods, namely:
a. Vapour compression refrigeration systems, including
i. Domestic refrigeration systems (Section 1.3.1.1)
ii. Air conditioning systems (Section 1.3.1.2)
b. Vapour absorption refrigeration systems (Section 1.3.2)
c. Solar energy based refrigeration systems (Section 1.3.3)
d. Air cycle refrigeration systems (Section 1.3.4)
e. Steam and vapor jet refrigeration systems (Section 1.3.5)
f. Thermoelectric refrigeration systems (Section 1.3.6), and
g. Vortex tubes (Section 1.3.7)

At the end of the lesson the student should be able to:
1. Identify various natural and artificial methods of refrigeration
2. List salient points of various refrigeration techniques, and
3. Name important landmarks in the history of refrigeration
1.1. Introduction
Refrigeration may be defined as the process of achieving and maintaining a
temperature below that of the surroundings, the aim being to cool some product or space to
the required temperature. One of the most important applications of refrigeration has been the
preservation of perishable food products by storing them at low temperatures. Refrigeration
systems are also used extensively for providing thermal comfort to human beings by means
of air conditioning. Air Conditioning refers to the treatment of air so as to simultaneously
control its temperature, moisture content, cleanliness, odour and circulation, as required by
occupants, a process, or products in the space. The subject of refrigeration and air
conditioning has evolved out of human need for food and comfort, and its history dates back
to centuries. The history of refrigeration is very interesting since every aspect of it, the
availability of refrigerants, the prime moversand the developments in compressors and the
methods of refrigeration all are a partof it. The French scientist Roger Thvenot has written an excellent book on the history of refrigeration throughout the world. Here we present only a brief history of the subject with special mention of the pioneers in the field and some important events.

Q:Which of the following can be called as a refrigeration process?
a) Cooling of hot ingot from 1000 C to room temperature
b) Cooling of a pot of water by mixing it with a large block of ice
c) Cooling of human beings using a ceiling fan
d) Cooling of a hot cup of coffee by leaving it on a table
e) Cooling of hot water by mixing it with tap water
f) Cooling of water by creating vacuum over it
Ans: b) and f)

1.2. Natural Refrigeration

In olden days refrigeration was achieved by natural means such as the use of ice or
evaporative cooling. In earlier times, ice was either:
1. Transported from colder regions,
2. Harvested in winter and stored in ice houses for summer use or,
3. Made during night by cooling of water by radiation to stratosphere.
In Europe, America and Iran a number of icehouses were built to store ice. Materials
like sawdust or wood shavings were used as insulating materials in these icehouses. Later on,
cork was used as insulating material. Literature reveals that ice has always been available to
aristocracy who could afford it. In India, the Mogul emperors were very fond of ice during
the harsh summer in Delhi and Agra, and it appears that the ice used to be made by nocturnal
cooling.
In 1806, Frederic Tudor, (who was later called as the ice king) began the trade in
ice by cutting it from the Hudson River and ponds of Massachusettsand exporting it to
various countries including India. In India Tudors ice was cheaper than the locally
manufactured ice by nocturnal cooling. The ice trade in North America was a flourishing
business. Ice was transported to southern statesof America in train compartments insulated by 0.3m of cork insulation. Trading in ice was also popular inseveral other countries such as
Great Britain, Russia, Canada, Norway and France. In these countries ice was either
transported from colder regions or was harvested in winter and stored inicehouses for use in summer. The ice trade reached its peak in 1872 when America alone exported 225000
tonnes of ice to various countries as far as China and Australia. However, with the advent of artificial refrigeration the ice trade gradually declined.

1.2.1. Art of Ice making by Nocturnal Cooling:

The art of making ice by nocturnal cooling was perfected in India. In this method ice
was made by keeping a thin layer of water in a shallow earthen tray, and then exposing the tray to the night sky. Compacted hay of about 0.3 m thickness was used as insulation. The water looses heat by radiationto the stratosphere, which is at around -55C and by early morning hours the water in the trays freezes to ice. This method of ice production was very popular in India

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