초록 ▼

The unknown amount or mass of liquid contained in a storage tank is measured by calibrating the tank in an empty and partially full condition. The calibration includes measuring the mass of the empty tank, and is accomplished by applying a measured amount of heater power or energy to the tank and it

The unknown amount or mass of liquid contained in a storage tank is measured by calibrating the tank in an empty and partially full condition. The calibration includes measuring the mass of the empty tank, and is accomplished by applying a measured amount of heater power or energy to the tank and its contents, and measuring the temperature response to determine the product of total mass multiplied by specific heat. The specific heat depends upon the mass or amount of liquid in the tank, but a linear relationship is established between total mass and the product of total mass times specific heat. The unknown mass of liquid is then determined by applying a known amount of heater power or energy to the tank and its contents, and measuring the temperature rise or rate of rise in response thereto. The mass of the system multiplied by specific heat is determined from the temperature rise or rate of rise, and is interpolated or extrapolated relative to the calibration to determine the mass of the system with its unknown amount of liquid. The mass of the tank is subtracted from the unknown system mass to determine the mass of the liquid. In a spacecraft fuel tank application, the tank-empty calibration is performed in an evacuated test chamber, and the partially-full calibration is performed on-orbit after one thruster burn has consumed an amount of fuel which is determined from a schedule based upon knowledge of the consumption of the particular thrusters or types of thrusters being used.

대표청구항 ▼

A method for determining the quantity of fluid in a tank, comprising the steps of: determining the mass of said tank in an empty condition for calibration; generating data representative of the specific heat of said tank, by applying a measured first amount of heat energy to said tank in an empty co

A method for determining the quantity of fluid in a tank, comprising the steps of: determining the mass of said tank in an empty condition for calibration; generating data representative of the specific heat of said tank, by applying a measured first amount of heat energy to said tank in an empty condition, determining the rise of temperature of said tank in response to said first amount of heat energy, and taking the quotient of said first amount of heat energy divided by the product of said temperature rise multiplied by said mass of said tank to establish a first calibration value; placing a known mass of said fluid in said tank to define a second calibration condition; generating data representative of the specific heat of said tank and its contents under said second calibration condition, by applying a measured second amount of heat energy to said tank and its contents in said second calibration condition, determining the rise of temperature in response to said second amount of heat energy, and taking the quotient of said second amount of heat energy divided by the product of said temperature rise in response to said second amount of heat energy multiplied by the sum of said mass of said tank plus said known mass of said fluid to establish a second calibration value; with an unknown mass of said fluid in said tank, applying a third measured amount of heat energy to said tank and its contents; determining the temperature rise of said tank and its contents in response to said third amount of heat energy to establish a datum value; one of linearly interpolating and extrapolating said datum value in relation to said first and second calibration values to determine the sum of said unknown mass and said mass of said tank to form an intermediate result; and subtracting said mass of said tank from said intermediate result to determine said unknown mass of said fluid.