US 12,313,593 B2
Method and device for determining antifreeze content in a fluid of an HVAC system
Forest Reider, Hinwil (CH); Stefan Mischler, Wald (CH); Volkher Scholz, Zürich (CH); and Philip Holoch, Neschwil (CH)
Assigned to BELIMO HOLDING AG, Hinwil (CH)
Appl. No. 17/802,284
Filed by BELIMO HOLDING AG, Hinwil (CH)
PCT Filed Apr. 27, 2021, PCT No. PCT/EP2021/060967
§ 371(c)(1), (2) Date Aug. 25, 2022,
PCT Pub. No. WO2021/219627, PCT Pub. Date Nov. 4, 2021.
Claims priority of application No. 497/20 (CH), filed on Apr. 28, 2020.
Prior Publication US 2023/0146901 A1, May 11, 2023
Int. Cl. G01N 29/024 (2006.01); G01N 29/44 (2006.01)
CPC G01N 29/024 (2013.01) [G01N 29/4418 (2013.01); G01N 2291/0222 (2013.01); G01N 2291/02809 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method for determining antifreeze content in a fluid of a heating, ventilation, and air conditioning (HVAC) system, performed by the HVAC system, the HVAC system comprising a control device and a sensor unit operatively connected to the control device, the method comprising:
measuring, by the sensor unit, the measurement data of the fluid;
receiving, in a processor of the control device, using a communication interface of the control unit, measurement data of the fluid measured by the sensor unit, the measurement data comprising a measured temperature of the fluid and a measured speed of sound in the fluid;
retrieving, in the processor, from a non-volatile memory of the control device, a defined relation between antifreeze concentration, temperature, and speed of sound;
calculating, in the processor, for each of a plurality of antifreeze concentration values a fitting parameter, as a function of:
the measurement data and the defined relation, and at least one of: previous measurement data of the fluid of the HVAC system or previous antifreeze concentration data of the fluid of the HVAC system,
each fitting parameter indicative of how well the antifreeze concentration value agrees with the measurement data and at least one of: the previous measurement data or the previous antifreeze concentration data; and
determining, in the processor, an antifreeze concentration in the fluid by selecting the antifreeze concentration value with an optimal fitting parameter, the optimal fitting parameter being a particular fitting parameter related to a best fit between the antifreeze concentration value, the measurement data and at least one of: the previous measurement data or the previous antifreeze concentration data.