By Vvon Engineering Team | Published | Updated
A practical guide to specifying an undergraduate thermal laboratory in Bangladesh: which experiments earn their floor space, how to instrument them, why steady state breaks your timetable, and what safety around heated equipment actually requires.
Scientific & laboratory RFQ checklist (TXT)
Heat-transfer equipment needs a specified heat source and heat-rejection arrangement. Confirm whether cooling comes from building water, a recirculating chiller or another approved source, and whether it delivers the required flow and temperature during the warmest operating conditions.
Thermal teaching equipment is less physically demanding than a fluids laboratory but more demanding on instrumentation and time. The three constraints that shape it are heat rejection, steady state and safety.
Map the department’s approved thermodynamics and heat-transfer syllabus to the required practicals. The following blocks are examples; the final selection and rig count depend on the course, timetable and existing equipment.
| Teaching block | Experiment | Rig type |
|---|---|---|
| Conduction | Linear conduction along a bar, radial conduction through a disc, thermal conductivity of insulating materials, contact resistance across a joint | Bench-top module, low utility demand |
| Convection | Free and forced convection from a flat plate, a pinned surface and a finned surface, effect of air velocity | Bench-top with a small fan or duct |
| Radiation | Stefan-Boltzmann relation, inverse square law, emissivity of different surfaces | Bench-top, needs a darkened corner |
| Heat exchangers | Concentric tube, shell and tube, plate and cross-flow units; parallel against counter flow; overall heat transfer coefficient and effectiveness | Floor-standing or trolley, needs hot and cold streams, for example the EDIBON TICC with its concentric tube, shell and tube, plate and cross flow modules |
| Boiling and condensation | Pool boiling regimes, filmwise against dropwise condensation | Bench-top, glass shrouded, needs care |
| Refrigeration | Vapour compression cycle on the pressure-enthalpy chart, coefficient of performance, effect of condenser and evaporator conditions | Trolley unit, for example the EDIBON TRCVC |
| Alternative cycles | Absorption refrigeration, heat driven rather than work driven | Trolley unit, for example the EDIBON TRAB |
| Fuels and combustion | Calorific value of solid and liquid fuels, flue gas analysis, air to fuel ratio, flame stability | Bomb calorimeter such as the EDIBON TBCF; combustion unit such as the TVCC |
| Air conditioning | Psychrometric processes, sensible and latent load, cooling and dehumidification | Floor-standing duct rig |
| Gas laws and cycles | Perfect gas relations, expansion processes, engine indicator diagrams | Bench-top and engine test bed |
A modular heat-exchanger system may share services across several exercises; confirm which exchangers and acquisition components are included. Fuels work can require separate analytical equipment: Eltra’s TGA THERMOSTEP supports thermogravimetric proximate analysis under a defined method. Fixed carbon is generally calculated by difference from the relevant fractions, not measured as a direct mass-loss step. Choose a carbon/sulphur analyser and combustion method for the actual fuel matrix rather than assuming an induction-furnace configuration suits every solid fuel.
Thermal rigs are mostly temperature measurement with a little flow and pressure attached. The instrumentation choices decide whether students learn measurement or just copy numbers off a screen.
Where computer acquisition is offered, confirm the sensor channels, sampling rate, control functions, export format and software licence. Different EDIBON units may use different systems; logging does not by itself increase the number of students who can operate a rig.
The practical compromise most departments settle on: first year and second year read instruments by hand and plot on graph paper, third year and final year use the logger and are assessed on what they do with the data. Specify the rig so both are possible. A unit whose sensor outputs are only visible inside proprietary software is a poorer teaching instrument than one with a panel display and a logged output.
Ask how cold-junction compensation and the complete temperature-measurement chain are verified. Set checks and calibration intervals for the required uncertainty and range. An ice-point or boiling-water check is only useful when performed with a suitable method and interpreted for pressure, impurities and the instrument’s operating range.
This is the scheduling problem nobody warns a new lecturer about. A conduction bar reaches steady state slowly. A shell and tube exchanger needs both streams stable before any reading means anything. A refrigeration unit needs the compressor to settle. In a three-hour slot with sixty students rotating through stations, a rig that takes forty minutes to stabilise will produce one usable data set, not five.
Thermal laboratories injure people in ordinary ways: contact burns, steam, pressurised glass and, occasionally, an oxygen cylinder handled carelessly. None of it is exotic, and all of it is preventable with a specification written before purchase.
Write these into the tender as requirements the supplier must meet, not as things you will sort out afterwards. Retrofit guarding is always uglier and usually gets removed.
Use the same arithmetic as any other teaching laboratory: cohort divided by working group size gives the number of stations that must run simultaneously, and the number of distinct experiments sets the rotation length. A section of sixty in groups of five needs twelve stations; a twelve-week rotation then covers twelve experiments once each.
Thermal work has one extra constraint. Some rigs cannot be run side by side without interfering with each other. A radiation experiment next to a hot air duct, or a free convection module beside a doorway with a ceiling fan above it, will give results that do not match theory and students will conclude the theory is wrong. Zone the room: still-air experiments in one area away from fans and openings, forced-flow and combustion rigs near the extract.
The room also gains heat. A dozen heated rigs running for three hours in a Dhaka April will make the space uncomfortable and will shift the ambient reference temperature that half the experiments depend on. Size the room ventilation or cooling for the connected heat load of the rigs, not for the number of occupants.
Three failure modes recur in this climate and all three are cheap to design out.
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