Introduction
The HILTON THERMO-ELECTRIC HEAT PUMP has beendesigned to enable students to inwestigate the performanceof a semi-conductor module which, on the application of anelectrical power supply, will produce a refrigerating effect.Though the power required to produce this cooling effect ishigh, modules of this type find applications in a variety ofhigh technology fields.
Conversely, by producing a temperature difference acrossthe module a direct conversion of heat to electrical energyresults.Again, due to inefficiency the power produced permodule is small but applications do exist where alternativesare either not available or impractical.
The usefull range of experiments that may be carried outwith the Thermo-Electric Heat Pump make it of interest tothose involved with courses in
Power Generation
Heat Transfer
lnstrumentation
Electronics
Refrigeration
Thermodynamics
Medicine
Astronautics
Aeronautics
Experimental capabilities
● lnvestigation of the effects upon the surfacetemperature of either face of the module withincreasing power supply (Peltier Effect).
● lnvestigation of the effect upon heat transfer ofreversing the polarity of the power supply (Thomsonor Lenz Effect).
● lnvestigation of the variation in open circuit voltageacross the module due to the variation in surfacetemperature difference (Seebeck Effect).
● Investigation of the power generating performance ofthe modulle with a steady load and increasing
temperature difference.
● Estimation of the coefficient of performance of themodule when acting as a refrigerator.
Background
Applications for thermo-electric devices of this type occurin fields where alternatives would be too bulky, heavy orimpractical.
When used in the refrigeration mode typical applicationsinclude scientific and aerospace instrumentation for coolingand reference temperatures, in the medical field for freezingtissue samples, and more recently in the micro-electronicsindustry for cooling component packages and small lasers.ln the reverse mode,application of the modules to powergeneration is generally only possible where the load is smalland alternative supplies are impractical. For this reasonsemi-conductor modules have found applications in remoteareas for powering radios and in nuclear driven power supplies for satellites.
Description
(Please refer to the schematic diagram on the opposite page)
The semi-conductor assembly is mounted on a heat sinkprojecting through the front face of the glass reinforcedplastic instrument panel.
The assembly consists of a module sandwiched betweenaluminium blocks giving both mechanical strength andthermometer wells for temperature measuremenL A nickelchrome alloy element heats the outer face of the cold sidealuminium block and this is thermally insulated within astainless steel casing-
Each of the experimental configurations described may beestabllished simply by sequenced switching of four controlswitches.
Variation of the power supplied to both the heater andsemi-conductor module is achiewed by separate long lifeheavy duty rheostats.
Measurement of the power supplied to the heater andrmodule is achieved by the use of separate ammeters andvoltmeters.A small lamp prowides a 'load" which may besvritched across the module in order to investigate thegenerating effect and a milli-ammeter and voltmeter allowmeasurement of the power generated.
Typical experimental results are shown graphically below.
