Die Erfindung betrifft ein thermisches Messgerat zur Bestimmung und/oder Uberwachung des Massedurchflusses eines fluiden Mediums (3) durch eine Rohrleitung (2) bzw. durch ein Messrohr mit zumindest zwei Temperatursensoren (11, 12) und einer Regel-/Auswerteeinheit (10), wobei es sich bei beiden Temperatursensoren (11, 12) um Widerstandselemente handelt, von denen zumindest eines beheizbar ausgestaltet ist, wobei die beiden Temperatursensoren (11, 12) in einem dem Medium (3) zugewandten Bereich eines Gehauses (5) angeordnet und in thermischem Kontakt mit dem durch die Rohrleitung (2) bzw. durch das Messrohr stromenden Medium (3) sind, wobei der Regel-/Auswerteeinheit zwei unterschiedliche Prazisions widerstande (R1, R2) zugeordnet sind, wobei der erste Prazisions widerstand (R1) einer ersten definierten Grose (Y1) und der zweite Prazisionswiderstand (R2) einer zweiten definierten Grose (Y2) entspricht, wobei die Regel-/ Auswerteeinheit (10) den an einem Widerstandselement (11, 12) ermittelten Widerstand (Rx1; Rx2) jeweils einer Messgrose (Y1; Y2) zuordnet, die auf einer Geraden (g) liegt, die durch zwei den Prazisionswiderstanden (R1,R2) zugeordnete Kalibrationspunkte ((R1, Y1), (R2, Y2)) verlauft, und wobei die Regel-/Aus werteeinheit (10) anhand der von den Temperatursensoren (11, 12) gelieferten Messgrosen (Y1, Y2) den Massedurchfluss durch die Rohrleitung (2) bzw. durch das Messrohr bestimmt.

Vorrichtung zur bestimmung und/oder überwachung des massedurchflusses eines fluiden mediums

The method involves measuring physical gas mixture property using a sensor. The complementary value of the thermal capacity is measured based on ratio between the flow rate and heat conductivity separately measured by gas quality sensor and microthermal sensor. The value of the thermal capacity is correlated with caloric value of the gas mixtures. An independent claim is included for microthermal sensor for determining physical gas properties.

Microthermal method and sensor for determining physical gas properties

We present a microelectromechanical systems-based sensor for the thermal detection of changes of gas mixtures such as the CO2 concentration in air that is of interest in air conditioning climate control within buildings. Key properties of the system are low power consumption (<; 10 mW) and high long-term stability through the absence of moving or consumptive components. The used sensor chip has three silicon-microwires (thermistors) surrounded by the gas mixture to be analyzed. A centered wire (heater) is supplied with sinusoidal heating power. This induces a thermal response via the surrounding gas to measurement wires (detectors) located in different distances from the heater. The phase shift between heating power and induced thermal responses at the detectors is analyzed and depends on the thermal properties of the gas. After calibration, the sensor is able to quantify the concentration of an individual component within a mixture of different but known gas components. This is demonstrated by measuring the CO2 concentration in N2/CO2 mixtures with a resolution of 0.2% at constant pressure and temperature.

Sensor for Thermal Gas Analysis Based on Micromachined Silicon-Microwires

The disclosure relates to a thermal mass flow meter for determining a material flow through a vessel. The mass flow meter has at least two measuring elements immersed into a vessel with a flowing medium, with one of the measuring elements being heated. It is proposed that the heated measuring element is arranged in front of the unheated measuring element in the flow direction of the medium for at least part of the time, and for part of the time the unheated measuring element is arranged in front of the heated measuring element.

Thermal mass flow meter and method for its operation

Die
Erfindung betrifft einen thermischen Massendurchflussmesser zur
Bestimmung eines Materialflusses durch ein Gefas.
Der Massendurchflussmesser weist mindestens zwei Messelemente auf,
die in ein Gefas mit stromendem Medium
eingetaucht sind, wobei eines der Messelemente beheizt ist. Es wird
vorgeschlagen, dass in Stromungsrichtung des Mediums zumindest
zeitweise das beheizte Messelement vor dem nichtbeheizten Messelement
und zeitweise das nichtbeheizte Messelement vor dem beheizten Messelement
angeordnet ist.

Thermischer Massendurchflussmesser und Verfahren zu dessen Betrieb

The invention relates to a method and a device for measuring gas consumption by means of a gas meter (1). A gas meter (1) comprising a thermal flow sensor (1a) for determining mass flow signals (SM) and a calibrating device used as an energy measuring appliance for emitting energy value signals (SE) is known. According to the invention, a gas type is determined by the gas meter (1) insofar as combustible and non-combustible gas mixtures (3) are differentiated. For a non-combustible gas mixture (3), the gas meter (1) is operated with calibration in mass units or units of volume under standard conditions (1/min), and for a combustible gas mixture (3), with calibration in energy units (kWh). Forms of embodiment include, inter alia, the measurement of a parameter (λ, α, c, η) of the gas (3) in order to determine the gas type; a gas quality sensor (1a) with the same structure as the thermal flow sensor (1a); and longer measuring intervals for a non-combustible gas (3) and shorter measuring intervals for a combustible gas (3). The advantages of the invention are, inter alia, reliable energy measurement as a result of the automatic differentiation between a non-accountable gas (3) and a high-quality useful gas (3); recognition of manipulation attempts; and automatic calorific value tracking even without calorific value measurement.

Thermal gas flowmeter comprising a gas quality indicator

Method for measuring gas consumption using a gas meter, especially for measuring gas energy consumption, whereby the meter is suitable for measuring both a gas mass flow and energy consumption in that the meter determines the gas type and if it is incombustible calculates a mass flow in weight or volume units, liters per minute (l/min), while if it is combustible calculates consumption in energy units, kWh. An independent claim is made for a gas meter that functions as both a mass flowmeter and an energy meter, having a gas quality sensor with means for determining a gas parameter that is indicative of whether the gas is combustible or not. To determine the gas type its heat conductivity, heat capacity, diffusivity or viscosity are calculated, from which the gas mixture can be determined.

Thermal gas flow measuring device with gas quality indicator

Method for measuring a fluid (3) mass flowrate in which a fluid (3) passes over a first thermometer (5a), a heater (6) and a second thermometer (5b). The heater is pulsed with selected time duration and power supply such that no thermal balance is achieved. For each thermometer: a characteristic temperature of a transient temperature signal is measured; from the measured characteristic temperatures for both thermometers a measurement signal is determined; and the mass flowrate is determined by comparison of the signal with a calibration value.

Device and method for transient thermal mass flow measurement

The invention relates to a method and a device for thermal measurement of the flow rate (v) of a liquid (3). In known thermal sensors, the heating capacity P is introduced in the form of rectangular pulses. According to the invention, the sensor (1b) is supplied by a heating control (2b) with non-constant heating pulses having a sublinear increase tendency P(t). A non-linear increase in the threshold value time (ts?) can therefore be at least partially compensated as a function of the flow rate (v) until it reaches a threshold value temperature (Ts). Several advantages of the invention are: improved measuring accuracy, reduced measuring time and a larger measuring range for the flow rate (v).

Method for thermal flow measurement with non constant heating pulses

The invention relates to a method and a device for thermal measurement of the flow rate (v) of a liquid (3). In known thermal sensors, the heating capacity P is introduced in the form of rectangular pulses. According to the invention, the sensor (1b) is supplied by a heating control (2b) with non-constant heating pulses having a sublinear increase tendency P(t). A non-linear increase in the threshold value time (ts<) can therefore be at least partially compensated as a function of the flow rate (v) until it reaches a threshold value temperature (Ts). Several advantages of the invention are: improved measuring accuracy, reduced measuring time and a larger measuring range for the flow rate (v).

Rolf Luchsinger

Papers

Thermal gas flowmeter comprising a gas quality indicator

Thermal gas flow measuring device with gas quality indicator

Device and method for transient thermal mass flow measurement

Method for thermal flow measurement with non constant heating pulses

Method for thermal mass flow measurement using non-constant heating pulses