Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

Glossary
Sealed system
A refrigerating system in which all refrigerant containing parts are made tight
by welding, brazing or a similar permanent connection; it contains no nonpermanent
connections.
Secondary (or indirect) cooling system
A system employing a fluid which transfers heat from the product or spaces
to be cooled or heated or from another cooling or heating system to the
refrigerating system without compression and expansion of the fluid.
Semi-hermetic compressor
A combination consisting of a compressor and electrical motor, both of which
are enclosed in the same housing, having removable covers for access, but
having no external shaft or shaft seals, the electrical motor operating in a
mixture of oil and refrigerant vapour.
Sensible heat
It is the amount of heat that causes a change in the temperature of substance
without changing its phase. It can be evaluated by means of temperature
reading device.
Servicing
All kinds of work that may be performed by a service technician, from
installation, operations, inspection, repair, retrofitting, redesign and
decommissioning of refrigeration systems to handling, storage, recovery and
recycling of refrigerants, as well as record-keeping.
Shut-off device
A device to shut off the flow of the fluid, e.g. refrigerant, brine.
Soft soldered joint
A joint obtained by joining of metal parts with metallic mixtures or alloys which
melt below 200 °C.
Soldered joint
A joint obtained by the joining of metal parts with metallic mixtures or alloys
which melt at temperatures in general less than 450 °C
Specific heat
The quantity of heat needed to raise a unit mass of substance by 1°C. It is
measured in joules per Kelvin per kilogram.
Strength test pressure
The pressure that is applied to test the strength of a refrigerating system or
any part of it.
Tightness test
The pressurisation of a refrigeration system, or any part of it, in order to test
for its tightness against leaks.
Ton refrigeration (TR)
It’s the common used unit for refrigeration or air-conditioning system capacity.
It is defined as the rate of energy required to melt a ton of ice at 0 oC in 24
hours. 1 ton of refrigeration (TR) = 3.517 kW = 12,000 Btu/h.
Total equivalent warming impact (TEWI)
A measure of the overall global-warming impact of equipment based on
the total related emissions of greenhouse gases during the lifetime of the
equipment, including its manufacture and the disposal of the operating
fluids and hardware at the end-of-life. TEWI takes into account both direct
emissions, and energy related emissions produced through the energy
consumed in operating the equipment. TEWI is measured in units of mass of
CO2 equivalent.
Transcritical cycle
A refrigerating cycle whose compressor discharges refrigerant at a pressure
above the critical point.
Transitional substance
Under the Montreal Protocol, a chemical whose use is permitted as a
replacement for ozone depleting substances, but only temporarily because
the substance’s ozone depleting potential is non-zero.
Ultraviolet radiation (UV)
Radiation from the Sun with wavelengths between visible light and X-rays.
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