HT19C – Free and Forced Convection

 

HT19C – Free and Forced Convection

The Armfield Free and Forced Convection unit has been specifically designed to demonstrate the phenomena of natural (free) and forced convection.

Description

The Armfield Free and Forced Convection unit has been specifically designed to demonstrate the phenomena of natural (free) and forced convection.

 

Hardware Description

The Armfield Free and Forced Convection unit has been specifically designed to demonstrate the phenomena of natural (free) and forced convection. Temperature profiles and heat flux over three different heat transfer surfaces can be easily studied.

The HT19 is designed for use with the Armfield HT10XC Heat Transfer Teaching Equipment.

This unit consists of a bench mounted vertical air duct positioned on the top of a centrifugal fan. The air duct incorporates an aperture positioned at the rear wall of the duct, into which three different types of heat-transfer surfaces can be inserted. The three types of heat exchanger supplied are; flat plate, cylindrical pins and finned surface.

Incorporating an electrical heating element, with positive thermal cut-out, and thermocouples for precise temperature measurement. The clamping mechanism ensures accurate alignment of the surface inside the duct. The front wall of the duct is acrylic, to allow viewing of the heated surface and measurement sensors.

For forced convection, the centrifugal fan draws ambient air upward through a flow straightener and over the heated surface. A manually variable throttle controls the air flow.

An air-velocity sensor measures the air velocity inside the duct upstream of the heat exchanger.

Thermocouples measure the air temperature before and after the heated surface, together with the surface temperature at three positions along the extended surface exchangers.

On the HT19 the heater power, the air flow rate and the configuration of the heated surfaces can all be controlled via the HT10XC, either from the front panel controls or from the software.

Technical Specifications

Features & Benefits

Downloads

  • Relationship between surface temperature and power input in free convection
  • Relationship between surface temperature and power input in forced convection
  • Understanding of the use of extended surfaces to improve heat transfer from the surface
  • Determining the temperature distribution along an extended surface
  • Comparing characteristics of a vertical and horizontal flat plate in free convection
  • Determining the characteristic velocity, the Reynolds, Grashof and Rayleigh numbers for a flat plate in free convection
  • Calculation of the average heat-transfer coefficient of the pinned heater in forced convection
  • Comparing horizontal and vertical configurations for a finned exchanger in free convection
Mimic Diagram showing the flat plate heated surface in the HT19

  • A bench-mounted unit specifically designed to demonstrate the phenomena of free and forced convection and to measure temperature profiles from three different heat transfer surfaces
  • Comprises a vertical air duct, with a transparent front for visibility mounted on a fan at the base of the duct, three heat transfer surfaces, air flow, and temperature probes
  • Technical data is included for each of the three heat transfer surfaces, which will enable students and researchers to compare practical results with theoretical analysis for free and forced convection
  • Three heat transfer surfaces supplied: a flat plate surface area 0.011m2, pinned extended surface area 0.0525m2, and finned extended surface area 0.1414m2
  • Vertical duct incorporates a transparent front wall allowing complete visualisation of the process and identification of the air flow and temperature sensors
  • Each heat transfer surface is fitted with its own heater (240W) and thermocouples, to enable easy interchange
  • All heat transfer surfaces incorporate guards to permit safe use outside of the duct for performing free convection experiments
  • ArmSoft software includes separate exercises for each of the heat transfer surfaces in free or forced convection and records of all measured variables for analysis and comparison of the performances
  • K-type thermocouples measure the air temperature in the duct before and after the heater, as well as the surface temperature of the heat transfer surfaces
  • The air flow is manually adjustable up to 10 m/s
  • The air flow is measured by an air-velocity sensor, which is inserted inside the duct
  • Mounted on a PVC baseplate which is designed to stand on the bench top and connect to the Heat Transfer Service Unit with simple plug-in connections
  • A comprehensive instruction manual is included

Electrical supply:
All electrical requirements are obtained from the HT10XC service unit.

NOTE: the supply rating of the HT19C must be the same as the HT10XC that it is used with, all electrical requirements are obtained from the service unit – HT10XC

PACKED AND CRATED SHIPPING SPECIFICATIONS

Volume: 0.1m³

Gross Weight: 12Kg

Length: 0.35m

Width: 0.30m

Height: 0.95m

HT19C-A: 230V / 1ph / 50Hz
HT19C-B: 115V / 1ph / 60Hz
HT19C-G: 230V / 1ph / 60Hz

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