Fundamentally, condensers and evaporators are heat exchangers where the refrigerant undergoes a state change. Condensers and evaporators must be properly designed and chosen in addition to compressors for any refrigeration system to operate smoothly. Considering everything, the two condensers and evaporators have a lot in common because they are essentially heat exchangers. Contrasts do, however, exist when the design is taken into consideration. In condensers, the refrigerant fume accumulates by discharging heat to an external liquid that functions as a heat sink.
With the exception of a few uncommon situations, like in cascade condensers, when the outside liquid (another refrigerant) dissipates, the outside liquid typically does not undergo any stage changes. The fluid refrigerant dissipates in evaporators by absorbing heat from an outside liquid (low temperature heat source). If the system is used to reasonably cool water, air, or another liquid, the outside liquid may not undergo state change, for example. There are several cooling and refrigeration applications where the outside liquid also changes condition. For instance, a typical summer cooling system dehumidifies the moist air by first combining water fume and then removing the heavy fluid water. Evaporators can freeze or ice up in a lot of low temperature refrigeration applications.
Condensers and evaporators alike must be designed with these angles in mind.
A crucial component of every refrigeration system is the condenser. The refrigerant enters a normal refrigerant condenser in a superheated state. It is initially desuperheated and then solidified by releasing heat to an outside medium. Depending on the temperature of the outside medium and the condenser’s design, the refrigerant may exit the condenser as a soaking or a sub-cooled fluid.
We’ll examine condensers’ classification next.
What group do condensers fall under?
Condensers go into one of several categories depending on the external liquid:
- Condensers that use air cooling
- Condensers cooled by water, and
- Condensers that evaporate water
Types of air-cooled condensers
As the name implies, air is the outside liquid in air-cooled condensers, meaning that the refrigerant rejects heat to the air flowing over the condenser. Natural convection type and Forced convection type are further categories for air-cooled condensers.
Type of Natural Convection Condensers
In condensers of the natural convection type, heat is transferred from the condenser according to the principle of lightness induced in conventional convection and radiation. The combined hotness move coefficient in these condensers is low due to the low air stream velocity and the moderate radiation heat transfer. As a result, it is anticipated that a reasonably large consolidating surface will expel a certain amount of heat.
Therefore, small limit refrigeration systems like home refrigerators and freezers use these condensers. Condensers of the normal convection kind are either of the finned tube or plate surface sort. The refrigerant transporting tubes are attached to the exterior walls of the refrigerator in plate surface type condensers, which are used in small refrigerators and coolers. With the exception of the entrance, the cooler’s entire body functions as a balance. Protection is provided between the cooler’s internal plastic front and the external cover, which functions as a balance. Consequently, the exterior of the refrigerator is always warm.
Type of Condensers with Forced Convection:
In forced convection condensers, a fan or a blower is used to maintain the airflow across the condenser surface. For efficient heat transfer, these condensers often incorporate balances on the air side. There are two types of balances: plate type and circular sort. Condensers of the constrained convection type are frequently found in water coolers, bundled air conditioning, and window-type forced air systems. These can be remote installed or case mounted. The compressor, Induction motor, condenser with condenser fan, accumulator, HP/LP cut-out switch, and pressure gauges are installed on a single case in the Chassis Mounted Type. Consolidating unit of evaluated limit is the name given to it.
The components are matched to produce the anticipated refrigerant mass flow rate to reach the estimated cooling limit. Vertical or rooftop installed level types of remote mounting are available.
The following type of condensers will be examined:
Type of Water Cooled Condensers
Water serves as the outer liquid in condensers of the water-cooled variety. Water cooled condensers can also be divided into the following categories, depending on the development:
Tube-in-tube or double pipe
Types of shell and coil
Shell and tube design
Condensers of the Double Tube-in-Tube Type
Condensers of the double pipe type are typically used up to a 10 TR limit. In this sort of condenser, cold water flows through the inner cylinder while the refrigerant flows counterclockwise through the annulus. To shorten the length of the condenser and reduce pressure drop, headers are used at both ends. A portion of the heat produced by the refrigerant in the annulus is lost to the environment by free convection and radiation. Due to unlucky fluid refrigerant waste in the case of long tubes, the hotness motion coefficient is normally poor.
Types of Condensers with Coils and Shells
These condensers are used in frameworks with a maximum TR rating of 50. The heat transfer coefficient is built when the water flows through a variety of curls that may or may not contain fins. The shell is drained of the refrigerant. In more modest limit condensers, water flows through the shell while refrigerant passes through coils. Cleaning is completed by circulating appropriate synthetic chemicals through the coils as water flows over them.
Types of Shell and Tube Condensers
This is the most well-known type of condenser, used in systems with a limit of 2 TR to thousands of TR. In these condensers, water passes through the tubes once to four times as the refrigerant travels through the shell. The lower portion of the shell is where the condensed refrigerant collects.
For smooth seepage of fluid refrigerant, a vent connecting the beneficiary to the condenser may be present. The shell serves as a recipient in addition. Additionally, the refrigerant also rejects heat from the shell to the outside elements. The flat shell kind is the one that is most well-known. In large limit systems, vertical shell-and-tube type condensers are typically used with ammonia so that the cylinders can be cleaned from the top while the plant is operating.
The third condenser type in the classification will be discussed next.
Types of Evaporative Condensers
Both air and water are used in evaporative type condensers to remove heat from the collected refrigerant. The benefits of a cooling tower and a water-cooled condenser are combined in evaporative type condensers as one single device. In these condensers, air is ignited upwards while water is sprayed from the top portion onto a bank of tubes carrying the refrigerant. Around the condenser tubes, where evaporative cooling takes place, there is a thin water coating. The evaporative cooling process has a colossal heat transfer coefficient. Consequently, low consolidation temperatures can be used to operate the refrigeration system (around 11 to 13 K over the wet bulb temperature of air).
The water splash acts as a cooling tower by pushing back against the wind current. Fundamentally, air’s function is to quicken the rate at which water evaporates. Condensers of the evaporative kind are used in medium- to large-limit structures. When compared to water cooled condensers, which need a distinct cooling tower, these are frequently less expensive. Where water is scarce, evaporative condensers are used. Because water is used in a closed circle, very little of it evaporates. To cover evaporative losses, make-up water is offered. Regularly, just 5% of a comparable water-cooled condenser with a cooling tower’s water usage, which is quite low.
The Atmospheric condenser is another simple type of condenser that is frequently used in older, more established cold stocks. The barometrical condenser’s operating principle is similar to that of an evaporative condenser, with the exception that no fans or blowers are used, and the wind current passes naturally across the condenser. Condenser tubes are covered with water splashed from a shower frame. The outside heat move coefficient is quite large since heat is moved outside the cylinders by both adequate cooling and vanishing.
This concludes the discussion of condenser classification; hopefully, it has helped you gain a better understanding of condensers and the various varieties used in HVAC systems.