Monitoring of oil concentration in a refrigeration cycle

Sensors for process optimization of CO2 scrubbers

Decades of experience show that measurements in research, especially in the refrigerant circuit, are complex and complicated. Sampling is often difficult or not possible at all. Therefore, the ratio between oil and refrigerant must be estimated by indirect methods.

The aim is to find out how efficiently a cooling system works depending on the oil concentration. The information obtained from the measurements provides insight into how the processes in the compressor take place and when it is no longer operational.

To conduct the measurements as precisely as possible, SensoTech has the inline solution LiquiSonic^® OCR developed, which brings unbeatable advantages.

What if the ratio between oil and refrigerant is known at all times and with high precision?
What if no elaborate samples had to be taken to determine the oil/refrigerant ratio?

Measuring the Refrigerant Circuit with Liquisonic® OCR

Through LiquiSonic^® OCR comprehensive information about the refrigerant process is continuously available. The permanent knowledge of the concentration ensures optimal process control, while the quick approach to the optimal oil/refrigerant ratio reduces the adjustment time.

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The optimal ratio of refrigerant and oil with LiquiSonic^® OCR efficiently determined

SensoTech makes it possible to have precise knowledge of the concentration of compressor oil in refrigerant at any time. Accurate inline measurements eliminate the need for elaborate and error-prone sampling. Measurements are available at any time and are updated every second.

Highest precision in monitoring oil in the refrigerant circuit

SensoTech places the highest value on precise measurements when monitoring oil concentration. The determination of the oil concentration is based on pressure, temperature, and sound velocity measurements in the liquid refrigerant. This highly accurate measurement principle enables precise adjustment of the desired oil circulation speed.

OCR system sensor, adapter, controller, remote sensor electronics

Continuous determination of oil concentration instead of point measurements

The great advantage of online oil condition monitoring is the permanent availability of the measurements. Due to the second-by-second updating of the data, the operator always has precise knowledge of the measured oil concentration. Time-consuming adjustments of the oil concentration in the circuit are a thing of the past.

Monitoring a variety of refrigerants with a refrigerant measuring device

SensoTech impresses with sustainable and comprehensive process solutions. A total of up to 32 product data sets (calculation models) can be stored in the controller. This makes it easy to handle a wide range of refrigerants with the LiquiSonic^® Measurement technology to monitor. Due to decades of experience and manufacturing of measuring devices, there is almost no refrigerant left that has not been measured by SensoTech.

Determination of the Oil Concentration in the Refrigerant with Liquisonic® OCR.

Selection of measured refrigerants

R134a
R407c
R410A
R744
R1234yf
R1234ze
R290 (Propane)
R1233zd (E)
R407A
R404A
R454-B
R454-C
R717 (Ammonia)

Selection of measured compressor oils

D11
ND12
PAG
ACC-HV
POE 68

Comprehensive support for the analysis of oil in the refrigeration cycle

Clarification of the framework conditions
First, it is discussed with the user which medium should be measured. The SensoTech engineers check whether the combination of refrigerant and oil is already present in the existing database. If this is not the case, the feasibility of the measurement is determined in the in-house laboratory.
Clarification of the specification for the measurement of oil in refrigerant
Once the measurement task is clear, specifics are clarified. Among other things, whether special materials, installation variants, or special accessories are required for monitoring in the refrigeration cycle. The developed for this application LiquiSonic^® OCR System already has, for example, a special measuring head and an adapter vessel. This equipment allows seamless integration into the refrigeration cycle.
On-site installation qualification at the refrigeration cycle
Upon request, SensoTech supports the entire process. Our application engineers check the correct installation of the measuring system and verify whether the initial measurements are running correctly.
Regular training and further education
For various applications, SensoTech offers additional webinars and training. This allows the operator to get to know the measuring system in advance or to discover new functions afterwards.
Provision of new datasets for oil in refrigerant
The LiquiSonic^® Measuring system is not limited to a specific refrigerant or oil. As part of investigations, various refrigerants, such as refrigerant R32 and R134a, are analyzed in the in-house SensoTech laboratory. The use of another refrigerant at a later stage poses no problem. For this, SensoTech simply calculates a new dataset, loads it onto the controller, and the oil content in the new refrigerant can be determined.
Consultation on follow-up projects
For questions about the projects or other applications, the competent team of SensoTech is available for consultation.

Practical application examples of already measured refrigerants

There are countless refrigerants in use worldwide. As a globally operating company, SensoTech has already realized numerous projects with partners.

Oil circulation rate in R410A

Mainly used in refrigeration and air conditioning systems as well as in heat pumps in buildings
Very precise inline determination of the oil concentration
Replacement refrigerant for banned R22 systems

Refrigerant analysis for R1234yf

357 times more climate-friendly than other used refrigerants
Used as a replacement for R134a in new cars
More efficient operation at higher temperatures
Used in automotive air conditioning systems

Oil in refrigerant R134a

Banned in new cars within the EU, therefore often used outside the EU
Worldwide use in automotive air conditioning systems
R134a is considered the standard reference worldwide

FAQ on determining the concentration of refrigerant oil

For questions about measuring the oil concentration in the refrigerant circuit or about the measurement system LiquiSonic^® OCR the competent team of SensoTech is available.

Frequently asked questions:

Why is sampling for determining the concentration of the refrigerant-oil mixture problematic?
A sampling to determine the concentration is inaccurate and cumbersome because the closed system is interfered with. In general, refrigerants evaporate as soon as they come into contact with air. The samples amount to about one liter. The analysis is carried out in the laboratory. The concentration of oil in refrigerant to be determined is only available after a considerable time and is only a snapshot. The missing sample quantity ensures that the determined measured value does not reflect the current concentration. The systemmust first settle again. Therefore, real-time inline monitoring is preferable to sampling.
What is the purpose of the oil in a refrigeration system?
The oil in the refrigeration system lubricates the compressor and ensures that it operates smoothly and does not get damaged. The perfect mix ratio of oil and refrigerant must be observed. The rule is: as little oil as possible, but as much as necessary. Too much oil can reduce cooling performance, among other things.
What happens if there is too much oil in the AC system?
If there is too much oil in the AC system, it results in a reduction of cooling performance. This reduction causes the AC system to function only partially, requiring more time to achieve the desired cooling or the desired temperature may not be reached.
What type of oil is used in the refrigerant?
There are a variety of combinations of oil and refrigerant used in different compressors. The exact type of oil used depends entirely on the compressor manufacturer, as the respective compressors are only suitable for certain oils.
Can the refrigerant in the air conditioning system be replaced with another?
While measurements can be made in any known refrigerant, not every air conditioning system can use any refrigerant. If a different refrigerant than the previous one is used, it can attack and damage the seals of the compressor.