Flow Boiling Demonstration | ThermoFlux-7091
The Flow Boiling Demonstration ThermoFlux-7091 is a thermodynamics laboratory unit for observing all seven flow boiling phases in a double-wall glass tube evaporator (1200 mm length, 13.6 mm inner diameter, 24 mm outer diameter) using a CFC-free non-toxic evaporation liquid. This flow boiling demonstration apparatus includes a 2 kW heater, circulating pump (1.9 m3/h, 58 W), water jet pump (16 mbar final pressure), copper coil condenser, vapour collector, and expansion vessel forming a complete hot water and evaporation circuit on a laboratory trolley. Flow rate, temperature, and pressure can be independently varied to investigate their effects on evaporation behaviour, with pressure measurement to 1.5 bar relative and temperature measurement to 400°C. Optional LabVIEW-based Software TF-7091 enables digital data acquisition and results calculation on any Windows operating system.
The Flow Boiling Demonstration ThermoFlux-7091 is a laboratory unit for observing and investigating the full spectrum of flow boiling and evaporation phases that occur in heated pipes, as found in water-tube boilers. This flow boiling demonstration apparatus uses a double-wall glass evaporation pipe to make all phase transitions directly visible, from single-phase liquid flow through bubbly, slug, annular, film boiling, drop, and single-phase vapour flow. A 2 kW heater, circulating pump, water jet pump, vapour collector, and copper coil condenser form a complete, self-contained evaporation circuit mounted on a laboratory trolley.
Product Overview
The Flow Boiling Demonstration ThermoFlux-7091 replicates the evaporation process occurring in water-tube boilers at a safe, observable laboratory scale using a CFC-free non-toxic evaporation liquid that begins to evaporate at 40 to 50°C. The central component is a double-wall glass tube evaporator, 1200 mm in length, with an inner diameter of 13.6 mm and outer diameter of 24 mm. Hot water flows through the outer pipe of the double-wall assembly, transferring heat to the evaporation liquid in the inner pipe. All seven characteristic flow boiling phases are observable directly through the glass: single-phase liquid flow, bubbly flow, slug flow, annular flow, film boiling, drop flow (mist), and single-phase vapour flow. The hot water circuit consists of a 2 kW heater (temperature range -100 to 400°C), an expansion vessel, and a circulating pump (max. flow rate 1.9 m3/h, max. head 1.5 m, power consumption 58 W). The evaporation circuit comprises the glass tube evaporator, a vapour collector, a water-cooled copper coil condenser, and a return pipe. A built-in water jet pump (required water pressure 0.5 bar, flow rate 4 to 12 L/min, final pressure 16 mbar) generates the partial vacuum needed to lower system pressure and reduce the evaporation temperature of the liquid. The evaporation liquid quantity is 0.5 L, operating within a pressure range of -1.0 to 1.5 bar relative. Pressure measurement covers -1 to 1.5 bar relative and temperature measurement covers -100 to 400°C. All pipe systems are clearly arranged on a metal panel mounted on a laboratory trolley with an HDF sheet surface. Optional Software TF-7091, developed in National Instruments LabVIEW, provides DAQ-based measurement and results calculation on any Windows operating system, with electronic sensors included when the software option is selected.
Technical Specifications
| Parameter | Detail |
|---|---|
| Model Reference | ThermoFlux-7091 |
| Category | Thermodynamics and Heat Transfer |
| Evaporation Liquid | CFC-free, non-toxic, evaporation onset 40 to 50°C |
| Evaporation Liquid Quantity | 0.5 L |
| Pressure Range (System) | -1.0 to 1.5 bar relative |
| Heater Power Rating | 2 kW |
| Heater Temperature Range | -100 to 400°C |
| Circulating Pump Max. Flow Rate | 1.9 m3/h |
| Circulating Pump Max. Head | 1.5 m |
| Circulating Pump Power Consumption | 58 W |
| Water Jet Pump Required Pressure | 0.5 bar |
| Water Jet Pump Flow Rate | 4 to 12 L/min |
| Water Jet Pump Final Pressure | 16 mbar |
| Tube Evaporator Length | 1200 mm |
| Tube Evaporator Inner Diameter | 13.6 mm |
| Tube Evaporator Outer Diameter | 24 mm |
| Evaporator Construction | Double-wall glass |
| Condenser | Copper coil, water-cooled |
| Pressure Measurement Range | -1 to 1.5 bar relative |
| Temperature Measurement Range | -100 to 400°C |
| Mounting | Laboratory trolley with HDF sheet, metal panel |
| Optional Software | Software TF-7091 (LabVIEW-based, Windows compatible) |
Technical Data
Heater
| Parameter | Value |
|---|---|
| Power Rating | 2 kW |
| Temperature Range | -100 to 400°C |
Circulating Pump
| Parameter | Value |
|---|---|
| Max. Flow Rate | 1.9 m3/h |
| Max. Head | 1.5 m |
| Power Consumption | 58 W |
Evaporation Liquid
| Parameter | Value |
|---|---|
| Type | CFC-free, non-toxic |
| Evaporation Onset | 40 to 50°C |
| Quantity | 0.5 L |
| Pressure Range | -1.0 to 1.5 bar relative |
Water Jet Pump
| Parameter | Value |
|---|---|
| Required Water Pressure | 0.5 bar |
| Flow Rate | 4 to 12 L/min |
| Final Pressure | 16 mbar |
Tube Evaporator
| Parameter | Value |
|---|---|
| Length | 1200 mm |
| Inner Diameter | 13.6 mm |
| Outer Diameter | 24 mm |
| Construction | Double-wall glass |
Condenser
| Parameter | Value |
|---|---|
| Type | Copper coil |
| Cooling Medium | Water |
Measuring Ranges
| Parameter | Value |
|---|---|
| Pressure | -1 to 1.5 bar relative |
| Temperature | -100 to 400°C |
Key Features
- Flow Boiling Observation: all seven evaporation phases directly visible through the double-wall glass evaporator on this flow boiling demonstration apparatus
- Glass Tube Evaporator: 1200 mm length, 13.6 mm inner diameter, 24 mm outer diameter, double-wall construction with hot water in outer pipe and evaporation liquid in inner pipe
- Evaporation Liquid: CFC-free, non-toxic, 0.5 L quantity, evaporation onset 40 to 50°C, pressure range -1.0 to 1.5 bar relative
- Heater: 2 kW power rating, -100 to 400°C temperature range
- Circulating Pump: max. 1.9 m3/h flow rate, 1.5 m head, 58 W power consumption
- Water Jet Pump: generates partial vacuum, 0.5 bar required inlet pressure, 4 to 12 L/min flow rate, 16 mbar final pressure
- Condenser: copper coil, water-cooled, part of closed evaporation circuit
- Hot Water Circuit: heater, expansion vessel, and circulating pump
- Evaporation Circuit: glass tube evaporator, vapour collector, copper coil condenser, and return pipe
- Mounting: laboratory trolley with HDF sheet surface and metal panel for clear pipe system layout
- Optional Software: TF-7091, LabVIEW-based DAQ software for measurement and results calculation on any Windows operating system
Experiments
Observation of typical forms of evaporation:
- Single phase liquid flow
- Bubbly flow
- Slug flow
- Annular flow
- Film boiling
- Drop flow (mist)
- Single phase vapour flow
Effect on the evaporation process by:
- Flow rate
- Temperature
- Pressure
Construction and Design
The Flow Boiling Demonstration ThermoFlux-7091 is mounted on a laboratory trolley with an HDF sheet surface, with all pipe systems clearly laid out on a metal panel. The double-wall glass tube evaporator (1200 mm length, 13.6 mm inner diameter, 24 mm outer diameter) is the central component, allowing direct visual observation of all flow boiling phases. Hot water produced by the 2 kW heater circulates through the outer pipe of the evaporator via the circulating pump (max. 1.9 m3/h, 1.5 m head, 58 W). The CFC-free evaporation liquid in the inner pipe is heated by the hot water flowing around it and begins to evaporate at 40 to 50°C. A built-in water jet pump (required inlet pressure 0.5 bar, flow rate 4 to 12 L/min, final pressure 16 mbar) generates a partial vacuum in the evaporation circuit, lowering system pressure to control the evaporation conditions. The evaporation circuit consists of the glass tube evaporator, a vapour collector, a water-cooled copper coil condenser, and a return pipe forming a closed loop. An expansion vessel is included in the hot water circuit. Pressure measurement covers -1 to 1.5 bar relative and temperature measurement covers -100 to 400°C across both circuits. This flow boiling demonstration apparatus interfaces with optional Software TF-7091, developed in National Instruments LabVIEW, for DAQ-based data acquisition, measurement, and results calculation on any Windows operating system, with electronic sensors included when the software option is selected.
Software
Software TF-7091 (Optional): DAQ software developed in National Instruments LabVIEW environment for measuring and calculating experimental results. Electronic sensors are included with the software option. Compatible with any Windows operating system.
Q1: What evaporation phases can be observed with the Flow Boiling Demonstration ThermoFlux-7091?
Seven phases are directly observable through the double-wall glass evaporator: single-phase liquid flow, bubbly flow, slug flow, annular flow, film boiling, drop flow (mist), and single-phase vapour flow.
Q2: Why is a double-wall glass tube used as the evaporator in this flow boiling demonstration apparatus?
The double-wall glass construction allows the evaporation process in the inner pipe to be observed directly and continuously. Hot water flows through the outer pipe to heat the evaporation liquid in the inner pipe, while the transparent glass makes all phase transitions visible without interrupting the process.
Q3: What is the purpose of the water jet pump in the ThermoFlux-7091?
The water jet pump generates a partial vacuum in the evaporation circuit, lowering system pressure to a final pressure of 16 mbar. This reduces the boiling point of the evaporation liquid, enabling controlled observation of evaporation at low temperatures (40 to 50°C) with a CFC-free, non-toxic fluid.
Q4: What parameters can be varied to study their effect on the evaporation process?
Flow rate, temperature, and pressure can each be independently varied to study their individual and combined effects on the flow boiling phases and evaporation behaviour.
Q5: Is data acquisition software available for the ThermoFlux-7091?
Yes. Optional Software TF-7091, developed in National Instruments LabVIEW, provides digital data acquisition, measurement, and results calculation. Electronic sensors are included when this option is selected, and the software runs on any Windows operating system.
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