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Air cooling for Vertex Detectors  [PDF]
Arantza Oyanguren
Physics , 2012,
Abstract: The vertex detectors are crucial detectors for future linear e+e- colliders since they must give the most accurate location of any outgoing charged particles originating from the interaction point. The DEPFET collaboration is developing a new type of pixel sensors which provide very low noise and high spatial resolution. In order to precisely determine the track and vertex positions, multiple scattering in the detector has to be reduced by minimizing the material in the sensors, cooling, and support structures. A new method of cooling by blowing air over the sensors has been developed and tested. It is applied in the design and construction of the Belle-II detector and may be used in the new generation of vertex detectors for linear colliders.
Thermoelectric Air Cooling For Cars  [PDF]
Manoj S. Raut,Dr.P. V. Walke
International Journal of Engineering Science and Technology , 2012,
Abstract: India is the second most populous country in the world with over 1.21billion people (estimated for April, 2011),more than sixth of the world’s population. India is projected to be world’s most populous country by 2025,surpassing china, its population exceeding 1.6 billion people by 2050.Comparing with the population there are 2.65 million cars sold in India as of march 2011.According to the society of Indian automotive manufacturer, annual car sales are projected to increase up to 5 million vehicles by 2015 and more than a 9 million by 2020.By 2050,the country is expected to top of the world in car volumes with approximately 611 million vehicles on the nation’s roads.The above data shows that, as the population increase the no. of vehicles also increase. Today, an automobile is a necessity for everyone. For a long or short journey people need car regard to thesafety, environment and most important comfort. Owing to these reasons, many vehicles are equipped with heating, ventilating and air conditioning system. In today’s world, no one feel comfortable in a vehicle without HVAC system. Therefore, HVAC becomes an integral part of human life. Today’s present HVAC system is very efficient and reliable but it has some demerits. It has been observed during the last two decades that the O3 –layer is slowly destroyed because of the refrigerant (CFC and HFC) used for the refrigeration and air –conditioning purposes. The common refrigerant used is HFC’s which are leaked and slowly climb into the atmosphere. When they reach to O3 layer they act on O3 –molecules and the layer of O3 is destroyed.
Improving the environmental cooling for air-coolers by using the indirect- cooling method  [PDF]
Farhan A. Khmamas
Journal of Engineering and Applied Sciences , 2010,
Abstract: Air-coolers are widely used as a cheap and convenient method for cooling; however, noise, humidity, smoking, and difficulty in controlling the interior temperature are its major disadvantages. In this research, we suggest using the indirect evaporative cooling method instead of the direct method. In this method the air-cooler is modified to operate as a cooling tower to produce cooling water by the evaporation process; this represents the outdoor unit. The cooled water is pumped to the indoor unit which consists of a fan coil unit. Many experiments were carried out to calculate the evaporation cooling effectiveness (ECE) in case of the direct and indirect cooling (forced or natural). The results for the two cases were compared. It is concluded that the ECE reduces by 15% for forced evaporation case, and by 22% for the natural case, as compared with the direct case and (with in 30/5/2008 and 16/6/2008).
A novel topology of EMI filter to suppress common mode and differential mode noises of electro magnetic interference in switching power supplies  [PDF]
P. Ram Mohan,M. Vijaya Kumar,O.V. Raghava Reddy
Journal of Engineering and Applied Sciences , 2007,
Abstract: This paper deals with Electro Magnetic Interference (EMI) in switching power supplies. The EMI consists of mainly common mode and differential mode noises. Due to interference, the efficiency of the equipment reduces and some times the equipment may be damaged. A procedure to design a novel topology of EMI filter to suppress these two noises is presented in this paper.
Impact of inlet air cooling on gas turbine performance  [cached]
Szymon Jarz?bowski,Ewa Pyzik,Andrzej Miller
Journal of Power Technologies , 2012,
Abstract: In this article different possibilities of gas turbine inlet air cooling were presented. The method of defining power gain caused by air cooling was discussed. The results of increasing power output level of several different turbines and one gas turbine in combine cycle in domestic ambient conditions were presented and discussed. Significant turbine power gains were received.
Detection of Legionella from Teaching Hospital Cooling Tower Water of Air Conditioning Systems in Eastern Province of Saudi Arabia  [cached]
Nasreldin Elhadi,Hatem Qutub
Asian Journal of Medical Sciences , 2012,
Abstract: The objective of this study was to investigate the frequency of contamination of Legionella in the King Fahd Hospital of the University (KFHU) cooling tower water of air conditioning system and other water supplies. A total of 300 samples were collected from various sites in KFHU. Water samples were collected from the cooling tower (88), hot-shower head (40), cold-shower head (59), engineering building (12) and drinking fountain (12). Swab samples were also collected from shower heads (44) and air ventilator (45). Overall Legionella was detected in only 5 (5.68%) out of 88 water samples and yielded 7 isolates. All other water samples that were collected from other sites were negative for the presence of Legionella. Culturing the hospital water supply for Legionella was the first step in the assessment of the risk for hospital-acquired Legionnaires’ (LD). Legionella is a common cause of hospital-acquired pneumonia, especially for immunocompromised patients.
Reducing the Array Size for DOA Estimation by an Antenna Mode Switch Technique
Shih-Chieh Cheng;Kun-Chou Lee
PIER , 2012, DOI: 10.2528/PIER12062203
Abstract: In this paper, an antenna-mode-switch technique is proposed to reduce the array size for the DOA (direction-of-arrival) estimation. Conventional DOA estimation requires many elements of antenna array to achieve high resolution, and then suffers from large array size. To improve such disadvantages, this paper proposes an antenna-mode-switch technique to reduce the required number of array elements. Numerical simulation shows that the required number of array elements will be greatly reduced by using the proposed technique. Furthermore, the bow-tie antenna design for implementing the proposed antenna-mode-switch technique is also given. The result proves that high-resolution and accurate properties of such a practical antenna design is very close to those of the ideal antenna mode.
Analysis of Broadband GaN Switch Mode Class-E Power Amplifier
Ahmed Al Tanany;Ahmed Sayed;Georg Boeck
PIER Letters , 2013, DOI: 10.2528/PIERL13012005
Abstract: Switch mode power amplifiers offer high efficiency approaching 100% for an ideal case. This paper discusses the operation mode of broadband switch mode class-E power amplifier designed previously by the authors for UHF applications (600-1000 MHz). A method to extract the waveforms at the die reference plane from the time domain analysis using 50 Ω environment systems is discussed. It has been observed that the designed class-E power amplifier operation was not maintained ideally over the entire band; however, it was operating close to the class-E operation.
Residual resistance simulation of an air spark gap switch  [PDF]
S. E. Siahlo,V. V. Tikhomirov
Physics , 2015,
Abstract: The numerical simulation of an air spark gap has been carried within two theoretical models. The kinetic one [1] allowed us to calculate time dependencies for the residual resistance (0.2 - 0.4 Ohm for our selection of a circuit parameters), the spark gap channel width, the electron number density, the mobility, the conductivity, the ionization degree, the magnetic field in the discharge channel, the channel inductance and the electron drift velocity. Simulating a real circuit and taking into account a spark gap residual resistance demonstrates good agreement of both models with the experimental data, while that without taking into account this resistance overestimates the maximal current in the circuit by approximately 5%.
Energy Efficient Air Conditioning System Using Geothermal Cooling-Solar Heating in Gujarat, India  [PDF]
Sneha Shahare, T. Harinarayana
Journal of Power and Energy Engineering (JPEE) , 2016, DOI: 10.4236/jpee.2016.41004
Abstract: It is well known that one unit of electrical energy saved is equal to more than two units produced. One way of economizing the power is utilization of energy efficient systems at all locations. In the present study, the air conditioning system is analysed and an innovative way is suggested. We use natural low temperature of shallow sub surface (1 - 3 m) of the earth—geothermal cooling system. It is known that majority of the households and the apartment complexes in India have two tanks for water storage. One is the underground water sump and the other is the overhead water tank. In our study, we use these two water storage systems for space cooling during summer and also for heating during winter. The main aim of our paper is air-conditioning of the space in an economic way to save electricity. It is based on a simple idea of transferring the low temperature from underground water sump to the room in the house using water as a mode of transport. Since India is a tropical country located at low latitude, most of the year, the air temperature is high and demands space cooling. However, for a couple of months during severe winter months (Dec.-Jan.) at Ahmedabad, heating of the space is required. For heating the space, we suggest to use the well-known solar water heater. Effective use of heat exchanger is shown through computation, modelling schemes and lab experiment. We recommend geothermal cooling for 10 months in a year and solar hot water system during 2 months of winter. It is observed that the ambient air temperature of 35°C - 40°C in the room can be brought down to 26°C without much consumption of electricity. In a similar manner, the room temperature at night (13°C) during winter in Ahmedabad can be increased to 27°C through circulation of water from solar water heater in the heat exchanger.
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