Repsol YPF

Definitions

Below you will find a list of basic technical terms, which will be used throughout this document:

• Cold:  the cold, by definition, does not exist. It is simply a sensation of a lack of warmth.
  
  
• Calorie:  a calorie is the quantity of heat that needs to be added to 1 kg of water at a temperature of 15ºC, in order to increase this temperature by 1ºC.
  
  
• Frigorie:  a frigorie is the quantity of heat that needs to be removed from 1 kg of water at a temperature of 15ºC, in order to decrease this temperature by 1ºC.
  
  
• BTU:  British Thermal Unit. This is the quantity of heat that needs to be removed from 1 lb of water in order to decrease its temperature by 1ºF. One BTU is equivalent to 0.252 kcal.
  
  
• Refrigeration ton:  This is equivalent to 3,000 F/h, and therefore, to 12,000 BTU.
  
  
• Thermal difference:  This is any difference between temperatures. It tends to be used to define the difference between the temperature of the air entering the air conditioner and that of the air leaving it and also to define the difference between the temperature of the air outside and that of the air inside.
  
  
• Comfort zone:  These are certain given temperature and relative humidity conditions, under which the majority of human beings feel comfortable. These conditions range between 22ºC and 27ºC for temperature and 40 and 60 percent for relative humidity.
  
  
• Humidity:  This is the condition of the air with regard to the quantity of water vapour that it contains.
  
  
• Liquid accumulator:  A receptacle situated before the compressor suction connection which carries out the double function of storing the surplus refrigerant from the evaporator in low temperature conditions and preventing liquid from entering the compressor, which would damage it.
  
  
• Battery:  This is the name for the evaporator and condenser when they are working with air.
  
  
• Compressor:  This unit compresses the coolant from the low pressure and temperature conditions at the evaporator outlet, to the conditions of the condenser. In general, this expression includes the compressor itself and the engine that powers it.
  
  
• Condenser:  This is an exchanger that transfers the heat produced to the medium that needs to be heated. Its construction characteristics depend upon the medium that is to be heated.
  
  
• COP:  Coefficient of Performance, the relation between the heat produced and the energy consumed in the compressor and the auxiliary equipment (ventilators, pumps, etc.). It varies according to the temperature conditions of the cold and hot sources that are being used.
  
  
• Evaporator:  This is the exchanger responsible for extracting the heat from the cold source (air or water). Its construction characteristics depend upon the medium from which the heat is extracted.
  
  
• Coolant or REFRIGERANT:  This is the fluid that is used in an air conditioning system to transmit heat, absorbing it at a low temperature and pressure and releasing it at a higher temperature and pressure.
  
  
• CFCs:  These are fluorocarbon refrigerants with two chlorine atoms.
  
  
• HCFCs:  These are fluorocarbon refrigerants with one chlorine atom and one hydrogen atom.
  
  
• HFCs:  These are fluorocarbon refrigerants with no chlorine.
  
  
• Calorific power or capacity:  The energy supplied in the condenser (kcal/h or kW). It varies according to working conditions.
  
  
• Refrigerating power or capacity:  The energy absorbed in the evaporator (kcal/h or kW or frigories). It varies according to working conditions.
  
  
• Ventilator:  This unit is responsible for moving the air, from or to which the exchanged heat can be extracted or transferred. They tend to be of the axial type in the exterior zone(evaporator) and of the centrifugal type in the interior zone (condenser), due to noise-related problems.
  
  
• Four-way valve:  This device is responsible for inverting the direction in which the refrigerant is moving, thus enabling the appliance to go from producing heat to cold and viceversa.
  
  
• Expansion valve:  This component is responsible for expanding the refrigerant that comes from the condenser until it reaches the conditions necessary to be able to enter the evaporator. It usually also, simultaneously, regulates the volume of refrigerant flowing through the machine.