Method and apparatus for correcting concentration

• US 5,315,376 A
• Filed: 10/11/1991
• Issued: 05/24/1994
• Est. Priority Date: 10/13/1990
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Jasco Corporation
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Jasco Corporation
• Inventors: Mizutani, Takehito, Hayashi, Kazuhisa, Kutsuna, Kiyoharu, Ebisawa, Kazunori, Nishimoto, Masashi, Watanabe, Mitsuo, Yuki, Yoshikazu, Wada, Akio
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): Keesee, LaCharles
• Application Number:
  US07/774,816
• Time in Patent Office: 956 Days
• Field of Search: 356/432, 356/128, 356/72, 356/43, 356/44, 356/45, 356/46, 356/47, 356/48, 356/436, 356/437, 374/131, 374/161
• US Class Current: 356/432
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction

Abstract

A concentration correcting apparatus comprising a correction coefficient calculating means and a correcting means is shown and described. The correction coefficient calculating means calculates a correction coefficient for correcting the concentration of the material when the actual density of the medium at the measurement of the material is calculated in terms of the density of the medium under the reference temperature and pressure, from the results of the temperature measuring means and the pressure measuring means. The correcting means corrects the results of the material measuring means to a concentration under the reference temperature and pressure on the basis of the correction coefficient. The measure value of the material in the medium under constant temperature and depressure is virtually calculated by correcting the measured value by using the correction coefficient while calculating the volume of the medium which is regarded as a parameter of a temperature and a pressure in terms of a volume under the constant temperature and pressure. It is therefore possible to calculate the concentration per unit weight under constant conditions even if the temperature and the pressure are varied at the time of measurement.

Claims

1. A concentration measurement correcting apparatus comprising:

a material measuring means for measuring the material which is an object of measurement in a medium as a density per unit volume;

a temperature measuring means disposed in the vicinity of said measuring means so as to measure the temperature of said medium;

a pressure measuring means disposed in the vicinity of said measuring means so as to measure the pressure of said medium;

a correction coefficient calculating means for calculating correction coefficient a₀, a₁ in the following equation (1) for correcting the density measurement of said material when the actual density of said medium at the measurement of the material is calculated in terms of the density of said medium at a reference temperature and pressure from the results of said temperature measuring means and said pressure measuring means on the basis of the following equations (2) and (3);

space="preserve" listing-type="equation">C=a.sub.0 +a.sub.1 ·

A (1)

wherein C represents a concentration, A the measured density of said material, ##EQU7## wherein P represents a measured pressure, T a measured temperature and α

_i, β

_i, γ

_i and δ

_i constants; and

correcting means for correcting the result of said material measuring means to a density measurement at said reference temperature and pressure by said correction coefficient.

2. The apparatus in accordance with claim 1 wherein the material measured has a volume which varies with pressure and temperature.

3. An apparatus according to claim 2,

wherein said material measuring means, said temperature measuring means and said pressure measuring means are disposed in a refrigerant carrier pipe in a refrigeration cycle;

and

said material measuring means measures the density of the oil contained in said refrigerant pipe.

4. An apparatus according to claim 2

wherein said material measuring means, said temperature measuring means and said pressure measuring means are disposed in a refrigerant carrier pipe on the excurrent side of a gas-liquid separator in the freezing cycle;

and

said material measuring means measures the density of the oil contained in said refrigerant pipe.

5. A method of correcting a concentration measurement comprising the steps of:

measuring the material which is an object of measurement in a medium as a density per unit volume;

measuring the temperature of said medium;

measuring the pressure of said medium;

calculating a correction coefficient for correcting the density measurement of said material when the actual density of said medium at the measurement of material is calculated in terms of the density of said medium of a reference temperature and pressure from the results of said temperature measuring means and said pressure measuring means; and

correcting the result of said material measuring means to a density at said reference temperature and pressure by said correction coefficient.

6. A method of correcting a concentration measurement comprising the steps of:

measuring the material which is an object of measurement in a medium as a density per unit volume;

measuring the temperature of said medium;

measuring the pressure of said medium;

calculating correction coefficients a₀, a₁ in the following equation (1) for correcting the density measurement of said material when the actual density of said medium at the measurement of the material is calculated in terms of density of said medium at a reference temperature and pressure from the results of said temperature measuring means and said pressure measuring means on the basis of the following equation (2) and (3);

space="preserve" listing-type="equation">C=a.sub.0 +a.sub.1 ·

A (1)

wherein C represents a concentration, A the measured density of said material, ##EQU8## wherein P represents a measured pressure, T a measured temperature and α

_i, β

_i, γ

_i and δ

_i constants; and

correcting the result of said material measuring means to a density at said reference temperature and pressure by said correction coefficient.

7. The method in accordance with claim 6 wherein the material measured has a volume which varies with pressure and temperature.