Vapour Absorption Refrigeration System (with diagram)! The power utilized in vapour compression system is high grade energy i.e., electric power for running the compressor motor. In absorption refrigeration system, however, heat is directly utilized as source of energy. Of course, it may be preferable to utilize heat as such as it avoids undergoing through the various energy transformations required in [...]
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 [...]
Large irrigation projects have been constructed all over the world for the purpose of irrigating agricultural lands through gravity flow systems. These projects usually consist of one or more storage reservoirs, diversion structures, canals and related structures, outlets and finally drainage facilities. The reservoirs constructed could also serve the purpose of flood control and hydroelectric power generation in which case [...]
With ever increasing demand of electric power, the existing transmission networks are found to be weak resulting in poor quality of unreliable supply. Also, it is realized that for expanding or enhancing the power transfer capability of the present transmission networks, huge sum of finances are required and sometimes even difficulties are encountered in finding right-of way for the new [...]
DC transmission possesses many technical and economic advantages over ac transmission. Some of the advantages are given below: Advantage # 1. Cheaper in Cost: Bipolar HVDC transmission lines require two-pole conductors while ac system requires 3 conductors to carry power. HVDC transmission can utilize earth return and, therefore, does not require a double circuit while EHV-AC transmission always requires a [...]
HVDC transmission is a strong alternative to EHV-AC transmission in some of the applications such as long distance high power transmission by overhead lines, under water transmission, transmission by underground cables, system interconnection by means of overhead lines or underground cables or back-to-back HVDC coupling stations, frequency conversion (50/60 Hz) and hence preferred. On the basis of applications, HVDC transmission [...]
The high voltage dc links may be classified into: 1. Monopolar Link 2. Bipolar Link 3. Homopolar Link. Type # 1. Monopolar DC Link: As the name suggests, monopolar link has only one conductor and return path is provided by permanent earth or sea. The line usually operates with negative polarity with respect to ground so as to reduce corona [...]
In HVDC transmission system or HVDC back-to-back coupling station, ac is converted into dc by means of a combination of converter-transformers and concerter valves. The conversion of ac into dc is called rectification. At the receiving end of the HVDC transmission line, dc is converted back to ac by means of converter valves and and converter transformers. The conversion of [...]
Fig. 7.8. shows an electric locomotive. It collects current from overhead equipment through sliding contact by means of a pantograph. The air circuit breaker is provided on the roof of the locomotive and its main function is to disconnect the locomotive from high voltage supply. Various Components of Electric Locomotive: 1. Over-head supply line 2. Pantograph 3. Circuit breaker. 4. [...]
In this article we will discuss about the functions of electric multiple unit and metro railways. Electric Multiple Unit (EMU): An Electric Multiple unit or EMU is a multiple unit train powered by electricity. The cars that form a complete EMU set can usually be separated by function into these four types. Power car, Motor car, Driving car and Trailer [...]