Power Blowers Research Articles

Analysis of bridge type and bridgeless cuk converter fed motor drives for improved power quality

ABSTRACT In the modern power electronic environment, application of low power, small size and high speed drives is achieving more prominence. In domestic appliances such as power tools, high speed fans, high power blowers etc., electric motors with high performance are attaining huge acceptance. The conventional variable speed drives employed diode bridge rectifier (DBR) and DC-to-DC converter-based methodologies, which hampered the supply by introducing current harmonics and conduction losses. This made these topologies unacceptable as per the standards set by the global power electronic authorities. Although there have been large number of developments in motors and control strategies, the risk and complexity of such drives become bottlenecks in implementation. In this paper, the conventional DBR-based DC-to-DC converter-fed drives are compared and analysed with a bridgeless dc-dc converter and a voltage source inverter-fed motor drive. Due to the low power, high-speed application of Brush Less DC (BLDC) motor, the same is selected for the aforesaid drive scheme. It is envisaged to ascertain that the combination of the same will help achieve almost near Unity Power Factor (UPF) and more efficient control compared to the conventional speed control topologies.

Development and Construction of a Fertilizer Rotary Dryer Using Waste Heat from an Electrical Generator in a Pig Farm

This research presents a study of the design and construction of a fertilizer rotary dryer in a pig farm which used waste heat at 400 degree Celsius from an electrical generator. The designed rotary dryer consisted of two pipes with lengths of 10 meters. These pipes consisted of a drying and a cooling pipe, each with a diameter of 0.5 meter. The power was supplied by two 5 horse power motors, and 2 horse power blowers were used to suck in hot and cool air for drying. The fertilizer, with an initial moisture content of 55-60 %db, was examined. Three parameters were varied to study the optimal condition of drying. These were rotary speed, degree of tilt angle and air flow rate. The rotary speed was varied at 10, 15 and 20 RPM, the degree of tilt angle was set at 1, 3 and 5 degrees, and the air flow rate was varied at 60, 120 and 180 cubic meters per hour. From the experiment, the result revealed that the condition of 1 degree of tilt angle, 10 rpm of rotary speed and an air flow rate of 180 cubic meters per hours were the optimal conditions for drying the fertilizer. The moisture in the fertilizer was reduced from 57.84 %db to 12.45 %db. The drying rate was 56.93 kg/h, and the thermal efficiency was 79.24 %. The energy consumption was 328.64 kWh/ ton. The capacity of the designed rotary dryer was 3 tons/day which is three times more than the amount of the traditional drying method. If the cost of the rotary dryer is 450,000 Baht, the payback period will be 3.73 months.

400 W High Temperature PEM Fuel Cell Stack Test

This work demonstrates the operation of a 30 cell high temperature PEM (HTPEM) fuel cell stack. This prototype stack has been developed at the Institute of Energy Technology, Aalborg University, as a proof-of-concept for a low pressure cathode air cooled HTPEM stack. The membranes used are Celtec P- 1000 series MEAs by Pemeas, with an active area of 45cm2. The low pressure gas channels enable the use of low power blowers instead of a compressor which increases the overall system efficiency. This initial system was made to test the bipolar plate design, and there is no need for humidification of the species as in a LTPEM fuel cell system. The use of the HTPEM fuel cell makes it possible to use reformed gas at high CO concentrations, still with a stable efficient performance.

Indoor pollutant mixing time in an isothermal closed room: an investigation using CFD

We report on computational fluid dynamics (CFD) predictions of mixing time of a pollutant in an unventilated, mechanically mixed, isothermal room. The study aims to determine: (1) the adequacy of the standard Reynolds Averaged Navier Stokes two-equation ({kappa}-{var_epsilon}) turbulence model for predicting the mixing time under these conditions and (2) the extent to which the mixing time depends on the room airflow, rather than the source location within the room. The CFD simulations modeled the 12 mixing time experiments performed by Drescher et al. (Indoor Air 5 (1995) 204) using a point pulse release in an isothermal, sealed room mechanically mixed with variable power blowers. Predictions of mixing time were found in good agreement with experimental measurements, over an order of magnitude variation in blower power. Additional CFD simulations were performed to investigate the relation between pollutant mixing time and source location. Seventeen source locations and five blower configurations were investigated. Results clearly show large dependence of the mixing time on the room airflow, with some dependence on source location. We further explore dependence of mixing time on the velocity and turbulence intensity at the source location. Implications for positioning air-toxic sensors in rooms are briefly discussed.

Tularemia on Martha's Vineyard: seroprevalence and occupational risk.

We conducted a serosurvey of landscapers to determine if they were at increased risk for exposure to Francisella tularensis and to determine risk factors for infection. In Martha’s Vineyard, Massachusetts, landscapers (n=132) were tested for anti–F. tularensis antibody and completed a questionnaire. For comparison, serum samples from three groups of nonlandscaper Martha’s Vineyard residents (n=103, 99, and 108) were tested. Twelve landscapers (9.1%) were seropositive, compared with one person total from the comparison groups (prevalence ratio 9.0; 95% confidence interval 1.2 to 68.1; p=0.02). Of landscapers who used a power blower, 15% were seropositive, compared to 2% who did not use a power blower (prevalence ratio 9.2; 95% confidence interval 1.2 to 69.0; p=0.02). Seropositive landscapers worked more hours per week mowing and weed-whacking and mowed more lawns per week than their seronegative counterparts. Health-care workers in tularemia-endemic areas should consider tularemia as a diagnosis for landscapers with a febrile illness.

New Suction Device for Sampling Arthropod Populations

A new suction sampler was constructed by equipping an Echo Power Blower with a special venturi attachment. The venturi uses energy of the blower exhaust to create suction in separate piping, similar to a flowing water aspirator. The external piping was modified by adding a cannister to hold the collecting net. The mechanical characteristics of this unit were compared to a standard Model lA backpack “D-vac.” The Echo was superior to the D-vac in suction, lighter in weight, had a more comfortable center of gravity, produced much less vibration, and was quieter. Comparative sampling studies in alfalfa showed the Echo to be equal or significantly superior to the D-vac in capturing a diverse complex of arthropods. Detailed plans are presented for the construction of the Echo sampling machine. Total cost for the base unit and modifications required is ca. $350.00.

Studies on Nicotiana Rustica as a Source of a Nicotine for Insect Control

This investigation had for its purpose the testing of the rate of volatilization of nicotine from ground Nicotiana Rustica (a high nicotine tobacco) in order to ascertain whether or not this type of tobacco could be used as an insecticidal dust. The ground tobacco was used alone, or with other materials. The rate of nicotine evolution was measured by the death rate or suspended animation of cabbage aphids ( Aphis brassicae Linnaeus) and other soft-bodied insects. As a result of these studies the following conclusions seem justified: (1) The ground tobacco, when used alone, with water or with basic lime compounds was not efficient as an insecticide in the control of aphids. (2) If sufficient quantities of basic materials were mixed with the ground tobacco, it was found that the addition of water resulted in the evolution of nicotine, the rate of evolution depending in a large measure on the amount of water added. (3) A mixture containing 5 parts of tobacco, 5 parts of hydrated lime and 3 parts of water proved to be very efficient as an insecticide under laboratory and field conditions. Notwithstanding the relatively large amount of water present, it was found that such a mixture could be applied to vegetation by the use of power blowers and with no especial difficulty. (4) Mixtures of the ground tobacco, water and basic lime compounds could be kept in sealed containers for a relatively long period of time with no apparent loss of toxicity. (5) These experiments warrant that some consideration be given to the possibility of cultivating Nicotiana Rustica for its nicotine content alone and to utilize it in the form of an insecticidal dust.