Refrigeration Sequence of Operation

A good understanding of the basic operation of the refrigeration system is essential for the service technician. Without this understanding, accurate troubleshooting of refrigeration system problems will be more difficult and time consuming, if not (in some cases) entirely impossible. The refrigeration system uses four basic principles (laws) in its operation they are as follows:

1.“Heat always flows from a warmer body to a cooler body.”

2.“Heat must be added to or removed from a substance before a change in state can occur”

3.“Flow is always from a higher pressure area to a lower pressure area.”

4.“The temperature at which a liquid or gas changes state is dependent upon the pressure.”

The refrigeration cycle begins at the compressor. Starting the compressor creates a low pressure in the suction line which draws refrigerant gas (vapor) into the compressor. The compressor then “compresses” this refrigerant, raising its pressure and its (heat intensity) temperature.

The refrigerant leaves the compressor through the discharge Line as a hot High pressure gas (vapor). The refrigerant enters the condenser coil where it gives up some of its heat. The condenser fan moving air across the coil’s finned surface facilitates the transfer of heat from the refrigerant to the relatively cooler outdoor air.

When a sufficient quantity of heat has been removed from the refrigerant gas (vapor), the refrigerant will “condense” (i.e. change to a liquid). Once the refrigerant has been condensed (changed) to a liquid it is cooled even further by the air that continues to flow across the condenser coil.

The RAC design determines at exactly what point (in the condenser) the change of state (i.e. gas to a liquid) takes place. In all cases, however, the refrigerant must be totally condensed (changed) to a Liquid before leaving the condenser coil.

The refrigerant leaves the condenser Coil through the liquid line as a warm high pressure liquid. It next will pass through the refrigerant drier (if so equipped). It is the function of the drier to trap any moisture present in the system, contaminants, and large particulate matter.

The liquid refrigerant next enters the metering device. The metering device is a capillary tube. The purpose of the metering device is to “meter” (i.e. control or measure) the quantity of refrigerant entering the evaporator coil.

In the case of the capillary tube this is accomplished (by design) through size (and length) of device, and the pressure difference present across the device.

Since the evaporator coil is under a lower pressure (due to the suction created by the compressor) than the liquid line, the liquid refrigerant leaves the metering device entering the evaporator coil. As it enters the evaporator coil, the larger area and lower pressure allows the refrigerant to expand and lower its temperature (heat intensity). This expansion is often referred to as “boiling”. Since the unit’s blower is moving indoor air across the finned surface of the evaporator coil, the expanding refrigerant absorbs some of that heat. This results in a lowering of the indoor air temperature, hence the “cooling” effect.

The expansion and absorbing of heat cause the liquid refrigerant to evaporate (i.e. change to a gas). Once the refrigerant has been evaporated (changed to a gas), it is heated even further by the air that continues to flow across the evaporator coil.

The particular system design determines at exactly what point (in the evaporator) the change of state (i.e. liquid to a gas) takes place. In all cases, however, the refrigerant must be totally evaporated (changed) to a gas before leaving the evaporator coil.

The low pressure (suction) created by the compressor causes the refrigerant to leave the evaporator through the suction line as a cool low pressure vapor. The refrigerant then returns to the compressor, where the cycle is repeated.

Suction	Discharge
Line	Line

Condenser

EvaporatorCoil

Coil

Metering

Compressor

Device

Refrigerant Drier Liquid

RefrigerantLine

Strainer

2009, 2008 specifications

Friedrich 2008 and 2009 represent significant advancements in heating and cooling technology, particularly in the realm of air conditioning systems. Friedrich is known for producing robust and efficient HVAC solutions tailored for both residential and commercial applications. These models are particularly noteworthy for their innovative features and energy-efficient technologies that enhance user comfort and lower operational costs.

One of the main characteristics of the Friedrich 2008 and 2009 models is their emphasis on energy efficiency. Both units are designed to meet or exceed Energy Star standards, which indicates that they use less energy compared to standard models, contributing to greener living solutions. The incorporation of efficient compressors and high SEER (Seasonal Energy Efficiency Ratio) ratings ensures that users save money on their electricity bills while enjoying optimal cooling performance.

The units also feature advanced inverter technology, which allows for variable speed operation. This means that the system can adjust its cooling capacity based on the current temperature needs, resulting in more consistent comfort while reducing wear and tear on the equipment. Additionally, the inverter technology operates more quietly compared to traditional systems, making these models suitable for both home environments and commercial settings.

Friedrich 2008 and 2009 also provide users with enhanced control options. The inclusion of smart technology and Wi-Fi connectivity allows for remote monitoring and temperature adjustments via smartphones or tablets. Users can create schedules, set temperature preferences, and receive maintenance alerts, contributing to a more user-friendly experience.

Moreover, these models are designed with robust construction, featuring durable materials that withstand various weather conditions. Their compact footprint and sleek design make them suitable for window installation, while an array of sizes accommodates spaces of different dimensions.

Additionally, the air filtration systems in Friedrich 2008 and 2009 units improve indoor air quality. They effectively capture dust, allergens, and other particulates, ensuring a healthier environment for occupants.

In summary, Friedrich 2008 and 2009 models stand out for their energy efficiency, innovative inverter technology, smart controls, and robust construction. With a focus on user comfort and environmental responsibility, these models provide reliable solutions for effective heating and cooling in diverse applications.