An air-conditioning device includes: a compressor; an outdoor heat exchanger; an evaporating unit configured to evaporate refrigerant a heater unit configured to heat the air by using the heat of the refrigerant a liquid receiver arranged at the downstream side of the outdoor heat exchanger and a restrictor mechanism provided between the heater unit and the outdoor heat exchanger, wherein, in an operation state in which the flow of the refrigerant is restricted by the restrictor mechanism and heat is released in the heater unit, a first operation mode and a second operation mode are switched, the first operation mode being set such that the liquid-phase refrigerant is stored in the liquid receiver and the gaseous-phase refrigerant is guided to the compressor and the second operation mode being set such that the liquid-phase refrigerant stored in the liquid receiver is guided to the evaporating unit.

A defrosting determination device includes: a condition specifying unit that specifies the air conditioning load condition corresponding to a pair of temperature inside the room and temperature outside the building based on condition information; a slope specifying unit that specifies the slope corresponding to the specified air conditioning load condition based on slope information; a frequency acquiring unit that acquires frequency information specifying the operation frequency of the motor; a calculation unit that calculates a threshold value by multiplying the operation frequency by the slope; a power information acquiring unit that acquires power information specifying power output to the motor; a decision unit that decides whether the power is equal to or less than the threshold value; and a determination unit that determines to start defrosting operation in response to the decision unit deciding that the power is equal to or less than the threshold value.

A defrosting control method for a multi-split system is provided. A multi-split system comprises an outdoor unit and multiple indoor units. An expansion valve is provided on a connecting pipeline between each of the indoor units and the outdoor unit. When the expansion valve of each activated indoor unit is closed and the degree of opening of the expansion valve of each off-state indoor unit is less than or equal to a maximum set degree of opening, the system satisfies a defrosting requirement, and as a result the method controls the expansion valve of each activated indoor unit to remain closed, thereby resolving the issue of a dramatic temperature drop in a room having an activated indoor unit during defrosting and improving user satisfaction. The degree of opening of the expansion valve of a off-state indoor unit is Off_PLS, and is controlled such that Off_PLS=ALL_HP*Avg_PLS/Off_HP. The invention satisfies a defrosting requirement and reduces the degree of opening of the expansion valves as much as possible, thereby preventing damage to a compressor without affecting defrosting.

A universal heat pump defrost controller device can be configured to determine when and for how long to cause a heat pump to enter defrost mode to remove ice from the outdoor heat exchanger coil. The defrost controller of this disclosure is configured to work with a variety of heat pumps which may implement a variety of defrost approaches, such as demand or timing. The arrangement and form factor of the defrost controller, along with break-away tabs, may allow the defrost controller to fit in the limited space available in many heat pumps. The simple dual display and controls of the device provide for intuitive configuration and troubleshooting during setup and installation.

According to certain embodiments, a system comprises a controller and an HVAC system with components comprising an evaporator unit comprising an evaporator coil, an indoor fan, and a discharge air duct and a condenser unit comprising a compressor, a condenser coil, and an outdoor fan. The system is configured to determine that a first or a second level of evaporator coil freeze risk is present and to communicate an instruction to the HVAC system with a first or a second action to counteract the freeze risk. For example, in certain embodiments, the actions comprise changing the indoor fan speed, changing the compressor speed, and changing the outdoor fan speed.

The present invention relates to a system for cooling a quick-freezing chamber at 40 to 30 C., a freezing chamber at 20 to 15 C., a refrigerating chamber at 0 to 5 C., and the like and an energy-saving defrosting system for defrosting the quick-freezing chamber, the freezing chamber, and the refrigerating chamber using condensed waste heat.

A refrigerator includes a storage chamber, an evaporator configured to cool the storage chamber, and an air passage through which cold air generated by the evaporator flows. The air passage includes a blower fan configured to blow the cold air to the storage chamber, and a trap part in which warm air generated by a defrosting operation stays, such that warm air generated by the defrosting operation is prevented from being introduced into the inner space of the refrigerator through the air passage. The refrigerator reduces the defrosting operation time, efficiently prevents increase of the inner temperature of the refrigerator due to warm air during the defrosting operation, reduces a temperature difference in inner temperature of the refrigerator, and prevents food stored in the refrigerator from being rotten due to a temperature change.

A method for defrosting an evaporator of a sealed system includes determining that a defrost cycle is needed to remove frost from the evaporator and initiating such a defrost cycle. The method further includes determining that the defrost cycle failed to defrost the evaporator and repeating the defrost cycle until the defrost cycle is successful or until a predetermined number of defrost cycles have been performed. After a predetermined number of successive failed defrost cycles, the method includes preventing further operation of the sealed system, e.g., by locking out compressor, until the frost and/or ice build-up is removed.

A system for heating a building via refrigerant includes a coil temperature sensor, an ambient temperature sensor, and a controller. The controller includes a processing circuit configured to record a system operating parameter and a control step of a control process before performing a sacrificial defrost cycle. The processing circuit is configured to cause the system to perform the sacrificial defrost cycle and operate the system at predefined system operating parameters other than the recorded system operating parameters. The system is configured to cause the system to operate at the recorded system operating parameters and generate calibration data in response to the sacrificial defrost cycle ending. The processing circuit is configured to cause the control process to operate at the recorded control step and cause the system to perform a defrost cycle based on the calibration data, the coil temperature, and the ambient temperature.

Ice mitigation for bridge cables is provided by a system having a plurality of heaters on one or more bridge cables, extending parallel to a longitudinal axis thereof, arranged in a plurality of heater sections, and configured to heat an outer surface of the bridge cables, and a control system including one or more controllers configured to individually activate and regulate heating output of the heater sections to prevent snow or ice from falling from the bridge cables. The heater sections can be arranged radially, about a circumference of the bridge cables, and/or axially, end to end along a length of the bridge cables, so that power can be individually directed to the heater sections to account for differing heating requirements at different radial and/or axial aspects of the bridge cables.