Laboratory Equipment

The test equipment used in the Heat Transfer and Fluid Flow Laboratory was developed here under long term experiences with industry cooling considering way of calculation, modeling and simulation. The equipment was designed to work with plenty of modifications that usually occur in industrial spray cooling applications; however the lab is flexible and able to develop and built equipment for measuring under very specific requirements.

When working in the lab, we learnt that the sophisticated measurement technology is essential for getting good results. Therefore we are continuously observing influences on the result data, following news in instrument technology, learning and improving. Heat Transfer and Fluid Flow Laboratory also participate in plenty of related projects e.g. development of new thermal and pressure sensors for rolling.

The high temperature test bench is used to simulate spray cooling at high initial temperatures. The typical application is continuous casting where the experiment usually starts at 1200°C and finishes below 500°C. The main part of the stand is a test plate, made of an austenitic steel, sized 600x320x30 mm. The test plate embedded by a set of thermocouples is during experiment stable while the nozzles spraying upward move under the plate. The spray height and nozzle velocity are variables.

• An electric furnace heats the test plate to an initial temperature of the experiment (1200°C).
• The water/air pressures in the nozzles covered by deflector are adjusted.
• When the furnace is put aside, the deflector is opened and the spraying nozzles start to move under the test plate according to requirements.
• The temperatures are recorded by thermocouples and saved to data logger located outside the spray box in a control room.

This experimental stand was built to study the cooling of linearly fast moving objects. The cooling of long rolled products (beams of various profiles) or the cooling of flat rolled products are typical industrial applications. Given that the movement of the stand is possible to stop at required positions for required duration, it is also oftentimes used for various other projects.

The stand allows speed of a tested sample up to 10 m/s, however the typical speed of 5 m/s is applied. The conception of a long girder with a draw trolley which can rotate around its longitudinal axis enables more sample positions respect to the gravity.

The girder is divided into three two-meter-long sections. The sections are used for the trolley’s acceleration or deceleration. The velocity of the trolley is constant in the mid section and it is here where the sample embedded by the thermocouples is quenched by the spray nozzles. The nozzle types, their arrangement and the feeding pressure together with the sample velocity are changeable parameters usually intended to be designed.

• A steel sample is heated to an initial start temperature in an electric furnace.
• The heated sample placed on the trolley is set up into the spraying position.
• The pump for the water gets going and the trolley controlled by computer runs several times through the cooling section under given conditions.
• The temperatures recorded by thermocouples in the steel sample are saved to data logger together with the trolley position.

This apparatus serves for measurement of cooling intensity vertically moving samples. The maximum weight of sample is 25 kg and can be moved by velocity up to 5 m/s which is constant for at least 1 m of its movement. The vertical bench is also equipped by furnace for heating of samples.

• A steel sample is heated to an initial start temperature in an electric furnace.
• The water pump is switched on and the water pressure is set up.
• The furnace is put away from the sample placed at the trolley.
• The trolley runs several times through the cooling section under given condition.
• Temperatures recorded by thermocouples in the steel sample are saved to data logger together with the trolley position.

The rotating test bench is designed for investigation of cooling effects on the rotating cylindrical surfaces. The parameters of the bench are adapted to the main application which is design of cooling systems of rolling-mill working rolls. The main part of the equipment is roll with diameter of Ø 650 mm and width of 600 mm powered by motor for pump station of 150 kW that allows rotational speed 0-5 rps. The roll is equipped by thermocouples measuring temperature while the roll surface is cooled by spraying nozzles.

There is a test segment located on the roll surface. This part of the perimeter is sophistically embedded by thermal sensors that are during spraying connected with datalogger. Only the neighbourhood of the test segment is heated to required initial temperature before the cooling experiment.

• An external electric heater heats the test segment of roll equipped by thermal sensors.
• When uniform starting temperature is reached, the heater is removed from the roll; the roll is covered by deflector.
• The rotation of roll, still covered by deflector, and the pump station are switched on and the coolant pressure is set up.
• When all experimental conditions are set up, the deflector is opened and the cooling starts.
• The temperatures are recorded by thermal sensors during cooling and saved to data logger.

Besides the rotating test bench with diameter of Ø 650 mm, another one with diameter of Ø 350 mm is available. The roll is placed in closed box with coolant loop that enables to test cooling characteristics of special chemicals.

Heating of metallurgical semi-finished products in preheating furnaces is a very energy-intensive process that can be optimized using mathematical models based on operational measurements.

Using a specially developed datalogger protection box, heating can be recorded up to 1350 °C/8 hours. We can design and realize operational measurements of heating and cooling modes for extended periods and various billet dimensions.

The billet can be fitted with up to 20 thermocouples (with special construction) for temperature measurement. Thermocouples are built into sensors that are inserted into the billet.

The special design of the thermocouples and their conduction in the thermally insulated trapeze makes it possible to distinguish inhomogeneities in heating less than 5 °C (no distortion due to conduction of thermocouples through the hot furnace atmosphere – typical of jacketed thermocouples).

The basis of the test chamber device with the dimensions 4x4x3 m and was made strictly in accordance with the Czech technical standard DIN EN 442-2 “Radiators: tests and evaluation”, which is the Czech version of the European Standard EN 442-2:1996. The whole device is designed to fully suit cited standard and thus allow measurement of heat output heaters in accordance with applicable legislation.

The operation of the test facility is secured by a complex system of heat pump, reservoirs of heat and cold, electric boilers, air handling and distribution systems in walls, floors and ceiling of the chamber. With the help of these components and a special computer program it is possible, basically in automatic mode, to measure and evaluate the performance of the heating or cooling element placed in the test chamber circle.

Detailed information (Read more): Calorimetric chamber ENG (PDF) Kalorimetricka komora CZ (PDF)

can be found in Publications of the Heat Transfer and Fluid Flow Laboratory.