US 8,978,445 B2Granted

System and a method relating to measuring humidity in a ventilated space

OwnerRikard Bergsteninventor

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Abstract

The present invention relates to a system and a method for measuring humidity in a ventilated space (3) comprising humidity sensing means (10), a heating device (201), and a control system (301) having access to pre-stored values on saturation vapor content of air at different temperatures. The relative humidity, Hrel(T1), at a first temperature, T1, is measured, with the heating device inactivate. For TI a pre-stored saturation vapor content value, Vsat(T1), is found. A first absolute humidity value, Vc(T1), is calculated by multiplying the first saturation vapor content value by the first relative humidity value. A second relative humidity, Hrel(T2), at T2 is measured, with the heating device on, a second vapor content value, Hsat(T2), at T2 is found and a nominal relative humidity value, RHnom, is calculated by dividing the first absolute humidity value, Vc(T1), by the second saturation vapor content value, Vsat(T2). The difference, ΔRH, between the second measured relative humidity value, Hrel(T2), and the nominal relative humidity value, RHnom is established and used to adjust subsequent relative humidity measurements for error compensation.

Claims18

Dependent claims

A system for measuring humidity in a ventilated space, comprising:

a sensing device that includes a humidity sensor and a temperature sensor configured for measuring relative humidity and temperature of air recirculated from the ventilated space;
a heating device;
a control system connected to the heating device and to the sensing device and including a memory configured for storing values of saturation vapor content of air at different temperatures,
wherein the sensing device is configured for measuring a relative humidity value Hre1(T1) at a first temperature T1;
the control system is configured for retrieving a saturation vapor content value Vsat(T1) for the first temperature and for calculating a first absolute humidity value Vc(T1) for the first temperature by at least multiplying the first saturation vapor content value by the first relative humidity value;
the sensing device is configured for measuring a second temperature T2 and a second relative humidity value Hre1(T2) at the second temperature that is higher than the first temperature;
and the control system is configured for retrieving a second saturation vapor content value Vsat(T2) for the second temperature, for calculating a nominal relative humidity value RHnom by at least dividing the first absolute humidity value Vc(T1) by the second saturation vapor content value Hsat(T2), for determining a difference ΔRH between the second relative humidity value Hre1(T2) and the nominal relative humidity value RHnom, and for adjusting subsequent relative humidity values of the sensing device based on the difference, thereby providing compensated relative humidity values.

4 more elements

A method of measuring humidity in a ventilated space, comprising:

(a) measuring a relative humidity in air recirculated from the space at a first temperature T1, thereby obtaining a first relative humidity value Hre1(T1);
(b) finding a saturation vapor content value Vsat(T1) representing a saturation vapor content of air at the first temperature;
(c) determining a first absolute humidity value Vc(T1) by at least multiplying the first saturation content value Vsat(T1) by the first relative humidity value Hre1(T1);
(d) increasing the temperature of the recirculated air with a heater;
(e) measuring the relative humidity in the recirculated air at a second temperature T2 higher than the first temperature, thereby providing a second relative humidity value Hre1(T2);
(f) finding a saturation vapor content value Vsat(T2) representing a saturation vapor content at the second temperature;
(g) determining a nominal relative humidity value RHnom by at least dividing the first absolute humidity value Vc(T1) by the second saturation vapor content value Vsat(T2);
(h) determining a difference ΔRH between the second relative humidity value and the nominal relative humidity value;
and
(i) adjusting subsequent relative humidity values based on the difference, thereby compensating measured relative humidity values.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/636,686Filed 22 Mar 2011
Priority: SE 105026523 Mar 2010
Published: US 2013/0008232 A110 Jan 2013
Granted: 17 Mar 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification18 codes

G05D 22/02
Control of humidity: characterised by the use of electric means
F24F 5/0046
Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00 , e.g. using solar heat or combined with household units such as an…
F24F 11/0001
Control or safety arrangements: for ventilation
F24F 11/30
Control or safety arrangements: for purposes related to the operation of the system, e.g. for safety or monitoring