SOLAS Refrigeration flashcards
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33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Refrigeration cycle
- A closed loop in which refrigerant is compressed, condensed, expanded, and evaporated to move heat from a cold space to a warmer surroundings.
- Evaporator function
- The heat exchanger where low-pressure liquid refrigerant boils and absorbs heat from the space or product being cooled.
- Condenser function
- The heat exchanger where high-pressure hot refrigerant vapour gives up heat to the surrounding air or water and condenses to liquid.
- Compressor role
- It raises the pressure and temperature of refrigerant vapour, creating the pressure difference that drives flow around the whole circuit.
- Expansion valve
- A metering device that throttles high-pressure liquid refrigerant to low pressure and controls the flow into the evaporator.
- Superheat
- The number of degrees a vapour is above its saturation temperature at the same pressure; measured at the evaporator outlet.
- Subcooling
- The number of degrees liquid refrigerant is below its saturation temperature at the same pressure; measured at the condenser outlet.
- Coefficient of performance
- The ratio of refrigerating effect produced to the work input of the compressor; higher values indicate a more efficient cycle.
- Saturation temperature
- The boiling or condensing temperature of a refrigerant at a given pressure; it rises as pressure rises and falls as pressure falls.
- Latent heat
- Heat absorbed or released during a change of state without a change in temperature, such as boiling or condensing refrigerant.
- Sensible heat
- Heat that changes the temperature of a substance without changing its state, such as warming air across a coil.
- Non-condensable gases
- Air or other gases that do not condense in the condenser; they raise discharge pressure and reduce system capacity.
- Refrigerant leak symptoms
- Low suction pressure, high superheat, bubbles in the sight glass, and reduced cooling capacity often indicate a refrigerant charge loss.
- Liquid line sight glass
- A window in the liquid line used to observe refrigerant flow; continuous bubbles suggest a shortage of liquid refrigerant.
- Moisture in system
- Water contamination can freeze at the expansion valve and form acids; filter driers and evacuation remove it during service.
- Evacuation
- Removing air and moisture from a system with a vacuum pump before charging, verified by holding a deep vacuum.
- Recovery of refrigerant
- Removing refrigerant from a system into a suitable container for reuse, recycling, or disposal rather than venting it to atmosphere.
- Air conditioning purpose
- It controls air temperature, humidity, cleanliness, and movement to provide comfortable or process-required indoor conditions.
- Dry-bulb temperature
- The ordinary air temperature measured by a thermometer exposed to the air, unaffected by moisture or radiant heat.
- Wet-bulb temperature
- The temperature of air measured with a wetted bulb; it reflects evaporative cooling and indicates moisture content and humidity.
- Relative humidity
- The amount of water vapour in air expressed as a percentage of the maximum the air could hold at that temperature.
- Dew point
- The temperature to which air must be cooled for water vapour to condense; cooling below it produces condensate.
- Latent heat of vaporisation
- The heat needed to change a liquid to vapour at constant temperature; for water it is about 2260 kJ per kg.
- Specific heat capacity
- The heat needed to raise one kilogram of a substance by one kelvin; for water it is about 4.18 kJ/kg·K.
- Heat load
- The total heat that must be removed from a space, including product, transmission, people, lights, and equipment gains.
- Ton of refrigeration
- A cooling rate equal to 3.517 kW, the heat needed to melt one short ton of ice in 24 hours.
- Pressure-enthalpy diagram
- A chart plotting refrigerant pressure against enthalpy, used to calculate refrigerating effect, work, and system performance.
- Discharge pressure
- The high-side pressure at the compressor outlet; it rises with condensing temperature and with non-condensable gases.
- Suction pressure
- The low-side pressure at the compressor inlet; it corresponds to the evaporating temperature and influences cooling capacity.
- Head pressure control
- Methods that maintain adequate condenser pressure in cold weather, such as fan cycling, dampers, or receiver pressure regulators.
- Thermostatic expansion valve
- A valve using a sensing bulb to regulate refrigerant flow and keep a set superheat at the evaporator outlet.
- Filter drier
- A device in the liquid line that traps moisture and solid particles to protect the expansion valve and compressor.
- Air-cooled condenser
- A condenser that rejects heat to ambient air moved across its coils by fans; capacity depends on air temperature and airflow.