reciprocating compressor, an oil separator, an air condenser connected
to a liquid receiver, a cartridge filter, a thermostatic valve
and a coaxial evaporator. The second loop is made up of the heating
circuit to be switched on by the evaporator. It consists of a gas
boiler that heats a water and ethylene–glycol mixture, with a device
for fluid accumulation, a three way valve and a circulation
pump. The whole system is provided with an on-line system to record
the main parameters such as temperatures, pressures and volumetric
flow rates.
The pressure and temperature of the working fluid are measured
and recorded at the inlet and exit of each device of the plant.
The mass flow rate is measured at the outlet of the liquid receiver
placed downstream from the condenser. The temperatures are recorded
through T-type thermocouples (copper–costantan), while
the pressure data is recorded through piezoelectric transducers
that convert the measured amount into a voltage signal standard
1–5 Volts.
The mass flow rates were measured in two different ways: a
mass flow meter with a Coriolis effect was used in the refrigeration
loop, while a turbine flow meter was used in the water–ethylene
glycol mixture loop.
The values of the different parameters were recorded and processed
by a data acquisition system that includes a thirty channel
data logger and a personal computer.
The heat transfer rate discharged in the evaporator is simulated
through the water–ethylene glycol mixture loop. Therefore the
mass flow rate and the relative temperature are measured at the
evaporator inlet section and at the evaporator outlet section