In my experiment, I'll use hot oil as the heat transfer fluid. Can I use a flow meter which is normally used with water? If I can use it, do I have to calibrate anything else?
Well, it will depend on the oil temperature. Normally in this case the temperature will conditione the instrumentation. The first and very easy way is the ultrasonic (panametrics) but you have to ask to manufacturer for the temperature range. The cheapest way could be mass calculation by temp difference in resistivity devices. The other method could be by using the coriolis acceleration. Finally a weight device could be used between two supports
for difficult mediums (hot corrosive etc.) you have flow-meters which work on the basis of the Von Karman vortex street. For instance this one is qualified from -200°C to +400°C and up to 40 Bar: http://www.de.endress.com/#product/72W
It depends on how much money do you want to pay. For hot oil, you should buy a flow meter with temperature compensation because the viscosity of oil is very sensitive to temperature. Otherwise, you should calibrate the sensor with respect to operation temperature range.
There are many types of Vortex or Venturi flow meters with temperature compensation but their price in the range of 1200 ~ 1500 $.
You can see the following manufacture website for more information.
If it is an open loop system, i would recommend use of Rotameter. Install it before the fluid enters the solar concentrator. This is the cheapest option. If you want to measure hot oil than vortex and Coriolis flowmeter are useful. Just check the viscosity of the oil as vortex meter has some specific range of viscosity for their operation. Coriolis is always a better choice if cost is not a deterrent.
Look at geared flow meters. The principle is the use of a gear motor which is equipped with a sensor giving a pulse when a tooth passes over.
They are used very often in hydraulic system to measure for instance the flow (and by integration the volume) to a cylinder and get the stroke. High precision since low leaks. I would place it on the entry (cold side). Cost is in general acceptable and dynamics as well.
.Now it depends how big is your flow. The Coriolis systems are as well for big flows.
For small flow rates and relatively low Reynolds numbers I have successfully used the integral orifice. They are relatively inexpensive and easy to operate. See my publication "EXPERIMENTAL FLOW MEASUREMENT WITH INTEGRAL ORIFICE" available on my ResearchGate profile.
- fluid temperature stay within limits as used at calibration (viscosity variations could if Reynolds value changes too much lead to changes in the flow coefficient and thus in the pressure drop)
- uncertainty is accepted in the range the device can supply the results
The positive aspect is the low cost (diaphragm + adapters + sensor+ conditioner)) and the fact that the measure is done by a pressure differential transmitter or if the pressure range and the tolerances are adequate by 2 usual pressure sensors which are low cost by definition.