The virtues of air refrigeration, including cheapness, availability and safety of the refrigerant used made it quite appealing to the early inventors of refrigeration machines. Air refrigeration dates back to the middle of nineteenth century, but it was not until 1877 that a reliable unit was developed. It was used mostly for cold-storage of meat on ships. However, the equipment [...]
Top 5 Methods of Refrigeration (Natural and Artificial Methods of Refrigeration)! 1. Natural Methods: (a) By Using Ice or Snow: The natural methods include the utilization of ice or snow produced naturally in cold climate. Ice melts at 0°C, so when it is placed in a space or system warmer than 0°C heat flows into ice and the space is [...]
In this article we will discuss about simple vapour compression refrigeration system. Introduction to Vapour Compression System: For a closed cycle of refrigeration employing the condensable refrigerant vapour, the following processes are required: (i) Compression of the vapour, thereby increasing pressure. (ii) Condensing these vapours and rejecting heating to the cooling medium (usually water or atmospheric air). (iii) Expanding the [...]
Learn about the comparison between Francis and Kaplan turbines. Comparison # Kaplan Turbine: 1. Kaplan turbine is a compact unit. 2. For a given head and output Kaplan turbine runs at a higher speed. 3. This is an axial flow turbine. 4. This turbine has a small number of blades (generally 4). 5. Loss of energy due to friction of [...]
In this article we will discuss about:- 1. Types of Semiconductors 2. Properties of Important Semiconductors 3. Preparation of Semiconductor Materials 4. Preparation of P-N Junctions Semiconductor Diode 5. Open-Circuited P-N Junction Semiconductor Diode 6. Forward Bias Arrangement 7. Reverse Bias Arrangement 8. Characteristics 9. Static and Dynamic Resistance 10. Breakdown Mechanisms. Contents: Types of Semiconductors Properties of Important Semiconductors [...]
In this article we will discuss about:- 1. Introduction to Junction Transistor 2. Operation of a Transistor 3. Current Amplification Factors 4. Transistor Leakage Currents 5. Characteristics. Contents: Introduction to Junction Transistor Operation of a Transistor Current Amplification Factors of a Transistor Transistor Leakage Currents Characteristics of Transistor 1. Introduction to Junction Transistor: The junction transistor consists of a silicon [...]
In this article we will discuss about combinational and sequential circuits and their functions. Introduction to Combinational and Sequential Circuits: A digital system must store binary numbers in addition to performing logic. To take care of this requirement, a memory cell, called a FLIP-FLOP, is introduced. Theoretically any digital system can be constructed entirely from NAND gates and FLIP-FLOPs. These [...]
In this article we will discuss about:- 1. Fabrication of Optical Fibres 2. Types of Optical Fibres 3. Formation of Light Guide or Optical Guide. Fabrication of Optical Fibres: Fibres used for communication are constructed from material systems which must satisfy the following requirements: i. The dielectric materials used must have low loss (<10 dB/km) in the infrared region of [...]
In this article we will discuss about:- 1. Introduction to C-R Oscillograph 2. Construction of CR Tube Used in C-R Oscillograph 3. Power Supply 4. Time Base or Sweep Circuits 5. Frequency and Phase Measurements. Contents: Introduction to C-R Oscillograph Construction of CR Tube Used in C-R Oscillograph Power Supply for C-R Oscillograph Time Base or Sweep Circuits Used in [...]
In recent years, the technique of producing high vacua has got great importance. Apart from its use in radio and X-ray equipment, it has helped us for investigating the behaviour of atoms and molecules under low pressure conditions. This has the reciprocal effect causing further improvements in exhaust pumps and high vacuum technique, in general. Today we can produce as [...]