Glossary of Terms

Here you will find a glossary of specialised terms commonly used in thermostating and metrology.

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T

Temperature control unit (TCU)

This is a comprehensive term for differently laid out heating or cooling systems that in a defined working temperature range can control temperature of the consumer by means of a liquid.

Temperature controller

Temperature controller is an active component that compares at least one temperature actual value with one setpoint, and depending on the deviation (see control deviation) outputs an adjusting command (see control variable). This so-called 'adjusting command(s)' acts on the so-called 'final control element(s)' which also actively triggers a measure that acts against the deviation. Temperature controllers can act purely mechanically (for example the so-called 'heating unit thermostat') or electronically - be set up analogue or digitally. Often several operating modes are combined.

Temperature stability

Half of the temperature difference between the highest and lowest temperatures which are measured for a specific set value after attaining a stable value within 30 minutes in one thermostat. The details are given at 70 °C (using water) for a heating thermostat and at -10 °C (using ethanol) for a cooling thermostat.

Through-flow cooler

Through-flow cooler is a mechanical or otherwise cooled heat exchanger, where a fluid positively flows through the system. The cooler mainly serves as a cooler for the fluid that is flowing through. Usually the positive flow is generated by a pump.

Through-flow coolers

Add-on coolers which are switched into an external circuit and upgrade the heating thermostats to heating/cooling thermostats. They are on the one hand used to replace water cooling, and on the other hand to reach lower temperatures (down to -40 °C with the DLK 45).

Through-flow heater

Through-flow heater is an electrical or otherwise heated heat exchanger, where a fluid positively flows through the system. The heater mainly serves as a heater for the fluid that is flowing through. Usually the positive flow is generated by a pump.

Two-circuit cascade refrigeration

This is a cascade connection of two refrigeration systems with cooling mediums (see refrigerant) of different thermodynamic properties. Two-circuit cascades with compression refrigerating processes are used at working temperatures below -50 °C. The first cascade (high-temperature stage) produces temperatures of about -35 °C in the evaporator. On the warm side of the evaporator the cooling medium of the second stage (low-temperature stage) condenses at about -30 °C and vaporises at about -90 °C, and is cooling the heat transfer fluid to about -80 °C.

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