Why ice forms at cooling coil and Suction line in Refrigeration system

 Why ice forms at cooling coil and Suction line in Refrigeration system

      it's all about the relationship between a temperature and pressure and how the pressure affect the boiling point of the refrigerant. As the pressure of refrigerant increases then the temperature and boiling point also increases,  when pressure decreased temperature and boiling point also decreases. Refrigeration and air conditioning systems take use of it to cool the air or liquid.

  Normal Refrigeration System 

    In normal refrigeration system compressor compresses the refrigerant which causes the increase in pressure and temperature of refrigerant. The hot vapour refrigerant pass through the condenser in condenser heat exchange happens and refrigerant condensate into liquid forms.Before entering in the evaporator high pressure liquid refrigerant pass through the expansion of valve. The actual device used depends on the Refrigeration system but capillary tube is common. 

    The liquid refrigerant forced through the expansion valve, in expansion valve sudden pressure drops of liquid refrigerant. Due to pressure drop temperature and boiling points also decreases. Then in the evaporator air or liquid which to be cool absorb the heat from refrigerant. Due to heat transfer refrigerant boils into a low pressure vapour refrigerant. Refrigerant leaves the evaporator in cool vapor state and again it goes toward the compressor.

 

Low air flows over the evaporator coil

   In evaporator in air conditioning systems warm air which is to be cooled is pass through the evaporator and the refrigerant removes the heat from the warm air and supply cool air to the required area.

  But if there is a insufficient air flows through the coil can cause the low heat exchange between the air and refrigerant. Due lower heat exchange refrigerant gets too cold which causes the refrigerant evaporator condensation start to freeze over evaporator and then to the Suction line upto compressor. 

Reasons behind the low air flows over the evaporator:-

   1) A clogged filter 

   2) Unhealthy blowers fan

   3) Choked finn's of evaporator coil

   4) leakage through air ducts 

   5) Closed or blocked air vents.

Low refrigerant 

  When the refrigerant in the Refrigeration system is low that its required limit, the pressure and therefore temperature also lower in Refrigeration system. When the refrigerant is low then the temperature of the refrigerant at the start of evaporator is lower than the freezing point of water. Because the cooling or evaporator coils are so cold the moisture or water drops condensation on evaporator start to freez. Due the freezing of condensation ice start to build on over the coils which restrict the air flow through the evaporator coils. Due the the restriction of ice cubes the refrigerant can't absorb as much as heat from air moving through coils. This causes the refrigerant to boil later in the evaporator due to which ice forms over the coils and this process continues until the whole evaporator forms a block of ice. After then the refrigerant start to boil in the Suction line. This cause to drop the temperature of Suction line and which start the freezing of condensation on the Suction line upto compressor. 

   Due the ice formation lot of trouble can happens in Refrigeration system. If allowed to operate to long in this condition,Which can damages the compressor.

 

Thermal Expansion Valve/Cap Tube

  A malfunctioning of refrigerant metering device like a bad thermal expansion valve can also cause the ice formation. 

  Conservely a bad capillary tube won't fail by passing too much Refrigerant but it might fail by passing the too little refrigerant it becomes blocked by debris or slugs of oil in the system. 

Check out similar posts below 

What is Refrigeration system 

What is refrigerant