An experimental prototype of an anemometer with PWM excitation is described. The instrument employs a thermistor as a flow detection sensor heated by a PWM voltage. An electronic negative feedback circuit substitutes the thermal power absorbed by the fluid from the heated sensor, and maintains it at a constant temperature. The pulse width contains the information about the fluid velocity and using a timer counter, the velocity information can be available in the digital form, without the use of a conventional A/D c0nverter.Tes.t results are also presented.
Over the past decade, electricity consumption in Brazil grew faster than generation capacity. This situation obliged an urgent return to investment in the sector, and revitalization of the restructuring in the national electricity sector. In these circumstances, the use of renewable energy sources, such the biomass, became an option for decentralized electricity generation. Sugar cane bagasse is one of the most important biomasss residues for electricity generation. The present publication analyses an investment made in the expansion of the energy cogeneration system in an industry that produces sugar and alcohol, from sugar cane, considering the seasonal bagasse price, energy generation costs and a 10 year period. With the new cogeneration system the factory became self-sufficient in energy, with a saleable surplus of 21,240 MWh, at an average power of 4,000 kW. However, an economic analysis indicated that the best option would have been to maintain the original system and sell surplus bagasse at R$ 26.00/t.
Calorimetric pyranometers use plane black thermal sensors which absorb solar radiation. If a thermoresistive transducer (sensor-detector combination) is used, the temperature measured is nearer the true value than for thermoelectric transducers. More importantly, the measurement of electrical power is much more accurate than the measurement of temperature. In commercial platinum (thermoresistive), thin film thermometers, the substrate produces transducer time constants an order of magnitude larger than for the best thermoelectric transducers. Use of an electronic amplifier with the thermoresistive sensor, forming one arm of a Wheatstone bridge and arranged in a negative feedback configuration, can reduce the overall response time considerably. Theoretical formulations of instrument response, taking into account the amplifier input offset voltage, are presented and the response time is estimated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.