Refrigeration systems consist of four major components, these are the compressor, condenser, expansion device (usually a TX valve) and evaporator. The evaporator is a heat exchanger used to transfer heat from the air of a refrigerated space to the refrigerant. Evaporators are usually constructed of a fin and tube coil, fan/s, a cabinet which includes a condensate drain. In rooms operating below 0°C heaters are included to defrost the coil.
Actrol have a variety of evaporators available to suit many different commercial and light industrial refrigeration applications. Typical applications include under-bar cabinets, display fridges, walk-in coolrooms, walk-in freezers, food processing applications and beverage cooling in restaurants, shops, supermarkets, take-away stores, food manufacturers, farms, pubs and clubs.
Medium and low temperature evaporator defrost cycles
Condensate will form on the evaporator coil as it operates below the dew point temperature of the air. In air conditioning this condensate will flow down the drain but in refrigeration the coil operates below 0°C so this water will freeze causing the evaporator to become inefficient over time.
In medium temperature applications an evaporator will defrost whenever the compressor cycles off as the refrigerated space temperature is above the freezing point of water.
Low temperature applications require preset defrost cycles. During a defrost cycle the compressor and evaporator fans are cycled off and the defrost heaters are cycled on. The defrost cycle is terminated by time or temperature and after a drain period the compressor is started followed by the evaporator fan/s. This ensures only cold refrigerated air is circulated within the refrigerated space.
It is common to offer more than one series or brand option as every project is different and each unit range has different benefits for the contractor and end customer.
Actrol evaporators can be put into two temperature categories and three type categories:
- Medium Temperature = used in refrigerated spaces above 0°C
- Low temperature = used in refrigerated spaces at or below 0°C
Cabinet coolers are designed specifically for reach in cabinets, glass door display cabinets, sandwich and pizza bar cabinets and other small applications. Actrol cabinet coolers are designed to have a small footprint and overall dimensions to maximise the usable space within the refrigerated cabinet. The air flows from the fan through the heat exchanger coil, this is called forced draft. Cabinet coolers are available in medium and low temperature versions.
Low Profile Evaporators
Low profile evaporators are designed for small walk-in coolrooms especially rooms with low ceiling heights and reach-in display rooms as found in liquor stores and take away food outlets. The low profile refers to the height of the evaporator unit. Most low profile evaporators are forced draft. (Air flows from the fan through the coil). Low profile evaporators are available in both medium and low temperature.
Walk in Coolroom and Freezer Evaporators
This is the most commonly sold evaporator and is used in coolrooms and freezers. Many models are available, as this style covers an enormous capacity range from very small walk-in rooms to large cold storage facilities with truck loading bays. The fan diameter and number of fans increases as the refrigeration capacity increases. Evaporators with less than 500mm fans are used in rooms with ceiling heights of less than 3m (metres). Evaporators with 500mm or greater diameter fans are used in rooms with ceiling heights of 3m or more, as larger diameter fans move more air. This style evaporator uses induced draft fans, so the air is sucked or induced through the heat exchanger coil. This increases the air throw to provide refrigerated air to every corner of larger refrigerated spaces. These evaporators are available in medium and low temperature versions.