Drift-free thermodynamic anemometry

Abstract

Advanced electronic metering of natural gas consumption is a new opportunity in the recent free market economy of the utility sector in the US and Europe. Real-time continuous measurements facilitate our awareness in the consumption of a non-renewable energy resource, which is a first step towards taking energy saving measures in domestic and commercial buildings. We here disclose a real-time desktop information system for natural gas consumption based on a new wireless electronic flow-meter. The meter is drift-free by subjecting thermal anemometry to a novel modulation technique. It uses a dynamical flow-interface to control the exposure of a thermal flow-sensor to a streaming medium. A discrete modulation of the flow perturbs the total heat-flux from the sensor to the medium. The relative perturbation, normalized to total heat-flux, creates a Nusselt number which is a function only of the Reynolds number of the flow. The medium temperature can be estimated on the basis of a similar factorization of the total heat-flux. Our method hereby measures both volume- and mass-displacement. In the preferred embodiments the interface consists of a by-pass configuration with micro-flow switches, controlling micro-jets applied to a silicon integrated flow-sensor. The device hereby forms a cost-effective and robust alternative to current approaches for electronic flow-metering. Its output is readily provided to a desk-top computer using existing wireless interfacing, serving energy-analysis and energy-saving strategies.

Description

REFERENCES [0001] 1. van Putten, A. F. P., & Middelhoek, S., 1974, Electron. Lett., 10, 425 [0002] 2. van Putten, A. F. P., 1975, Device for measuring the flow velocity of a medium, U.S. Pat. No. 3,996,799 [0003] 3. van Putten, A. F. P., 1985, Ambient temperature compensated double bridge anemomenter, U.S. Pat No. 4,548,077 [0004] 4. van Putten, M. J. A. M., van Putten, M. H. P. M., & van Putten, A. F. P., 1994, Sensors & Actuators, 44, 13 [0005] 5. van Putten, M. H. P. M., van Putten, M. J. A. M., van Putten, A. F. P., & van Putten, P. F. A. M., 1995, U.S. Pat. No. 5,426,969 [0006] 6. van Putten, A. F. P., van Putten, M. J. A. M., & van Putten, M. H. P. M., 1996, Measurement Science and Technology, 7, 1360 [0007] 7. van Putten, M. J. A. M., van Putten, M. H. P. M., van Putten, A. F. P., Pompe, J. C., Bruining, H. A., 1997, IEEE T. Biomed. Eng., 44, 205 [0008] 8. van Putten, M. J. A. M., van Putten, M. H. P. M., & van Putten, A. F. P. van Putten, 1999, IEEE T Instruments and Measure...

AI Technical Summary

Benefits of technology

"The patent describes a new method for measuring flow using a single silicon chip with thermal feedback control. This chip has bi-directional sensitivity to flow, making it insensitive to pressure changes. The sensor uses an Alternating Direction Method to measure the flow-induced Nusselt number, which is proportional to the Reynolds number of the flow. The sensor is designed to be highly sensitive to changes in temperature, and the temperature dependence of the Nusselt number is measured experimentally. The method is accurate and reliable, and can be used for metering domestic gas usage. The sensor is also designed for wireless data transmission and can be calibrated using a by-pass configuration with a thermal sensor and a dynamic flow-interface for discrete modulation of micro-jets."

Problems solved by technology

This hampers the process of bringing data “inside” (in the US) or “out of the closet” (in Europe) to the desktop.

However, these initiatives have as yet to produce commercially viable alternatives to existing mechanical meters.

This introduces inevitably an uncertainty in the caloric content of gas used, as determined by the displacement of mass of natural gas.

For example, systemic discrepancies in temperatures at purchase of natural gas by a gas distributor and at supply to a consumer introduces a systemic discrepancy in the expected caloric content payed for by the latter.

The bellow-meters hereby do not guarantee “pay for what they get” in true heat. unless these devices are temperature compensated.

However, practical realizations have proven to be challenging in view of drift in response to temperature changes of the medium and the device, wherein the latter may have a variety of time-constants.

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