Description
For comprehensive studies into the principles and performance of heat exchangers. The equipment allows students to quickly assess heat transfer rates by forced convection. They monitor the rate of cooling of a body of known thermal capacity in an air fl ow. The apparatus is bench mounting. It is a horizontal wind tunnel with a contraction cone, a working section, a diff user, a constant speed fan, and an exhaust with silencer. A variable slide valve controls the air fl ow. The working section includes a series of rods arranged in a matrix and at right-angles to the direction of air fl ow. To do experiments, students can remove any one of these rods and replace it with a cylindrical copper element. The copper element is of known thermal capacity and includes a built-in thermocouple. Students insert the element, which has been pre-heated to a specifi c temperature, into the working section at a known air velocity. They measure the time taken for the temperature to drop and determine the heat transfer rate. A second thermocouple at the inlet to the wind tunnel measures the temperature of air entering the heat exchanger. The base of the working section includes two static pressure tappings: one before the rods and one afterwards. These enable students to measure the static pressure diff erence across the rods. A Pitot traverse can measure air velocity at any vertical point in the working section, either before or after the rods. The equipment includes a separate instrumentation unit. The instrumentation unit has two inputs for the thermocouples, and two pairs of quick-release couplings for connection to the pressure tappings. It also includes a controlled heat source for the copper element. A digital display on the front of the instrumentation unit allows students to view all experimental data. In addition, the equipment is fully compatible with Versatile Data Acquisition System (VDAS®), and can quickly and conveniently connect to a bench-mounting interface unit (VDAS-B not included). Using VDAS® enables accurate real-time data capture, monitoring, display, calculation and charting of all relevant parameters on a computer (PC available separately).
Learning outcomes
- Determining the pressure losses created by the heat exchange rods and creating a chart of pressure drop against upstream pressure
- Calculating the inlet velocity and the mean velocity through the rods
- Determining the rate at which the heated rod cools down, within a bank of rods and by itself
- Plotting ‘cooling curves’ and using them to fi nd the coefficient of heat transfer (h) for the heated rod at various positions in the heat exchanger
- Determining the velocity distribution (profile) downstream of the rods
- Converting results into dimensionless values (typically using Nusselt, Prandtl and Reynolds equations)
- Comparing results and producing heat transfer coefficient curves
Specifications
ATICO is committed to a programme of continuous improvement; hence we reserve the right to alter the design and product specification without prior notice.
Nett dimension and weight
• Main part (assembled) – 1530 mm long x 1160 mm highx 400 mm front to back and 55 kg
• Control and Instrumentation unit – 615 mm wide x 220 mm high x 360 mm front to back and 16.5 kg
Approximate packed volume and weight:
0.79 m3 and 144 kg
Heat element:
• Diameter nominally 12.4 mm
• Material: copper
• Built-in thermocouple: K-type
Operating Conditions
Operating environment:
Laboratory
Storage temprature range :
–25°C to +55°C (when packed for transport)
Operating temprature range :
+5°C to +40°C
Operating relative humidity range :
80% at temperatures < 31°C decreasing linearly to 50% at 40°C
