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In order to investigate fan performance in fan-ventilated greenhouses (Urbana, USA), the effects of guard screen and loose belts on fan ventilation airflow and power consumption in greenhouse operations were examined with four belt-driven fans as trial subjects. The Fans Assessment Numeration System was used to measure the airflow rate. Temperature, relative humidity and power consumption were also monitored. Results show there were significant differences in the airflow rate between the fans with a cleaned and uncleaned guard screen (P<0.05). Power consumption also differed significantly even with the same cooling effect in greenhouse. When fan belts were adjusted to the proper tension, the fan speed and airflow rate were 13.1% and 30.1% higher than those of original belts, respectively. The daily average power consumption for the fan with the original loose belts was 20.4% higher than that with the adjusted belts when the pad was not working and 24.2% higher with pad working. The ventilation performance of fans with identical specifications showed a variation by up to 13.0% in terms of the ventilating efficiency ratio. These results demonstrated that fans should be cleaned routinely, and belt tension should be checked to ensure that fan performance meets specifications. This can reduce the power consumption in greenhouses for environmental control. Moreover, reordering fan staging, so that the most efficient fans are used in areas of greatest demand, can also reduce ventilation energy costs. [ABSTRACT FROM AUTHOR]

In order to properly analyse the operation of a two-level multichannel cyclone. a study on how air flow moves inside the cyclone is necessary. The two-level multichannel cyclone is designed to separate solid particles from the air stream and has been built in the Environmental Protection Laboratory at Vilnius Gediminas Technical University. Researches on finding how the air flow distributes within two levels and channels of the six-channel cyclone were made. Air velocity was measured using multimeter Testo-400 and dynamic Pito tube. Air velocity measurements in ducts before and after the device were done using an anemometer. The results showed that the air volume at both cyclone levels were equal, and air velocity in the channels that were the same at both levels was also distributed equally. The highest air speed was measured at the end of the last IV channel and reached 13 m/s. Minimum air velocity can be observed when the rings are arranged in such way that 75% of the air flow returns to the previous channel, and the maximum speed is when the previous channel returns 25% of the air flow. [ABSTRACT FROM AUTHOR]