Patent Application
20210055023
This disclosure relates generally to the field of vapor cycle machines and more particularly to a refrigerant filtration and drying functions (FDF) having a bypass loop and valve on a vapor cycle machine allows for continuous operation even during critical filter dryer end of life or failure conditions.
Aircraft, as well as other transportation and general heating ventilation and air conditioning (HVAC) systems, used in both commercial and private settings, employ vapor cycle machines. Modern commercial aircraft may feature a highly integrated air conditioning and pressurization system. Commonly, traditional air cycle based packs are utilized as a principal cooling plant for the airplane interiors. In some adaptations, this can be augmented by centralized or distributed smaller cooling units which are commonly a vapor cycle machine (VCM). In a VCM, work performed on a refrigerant enables air to ultimately be cooled in a heat exchanger (refrigerant evaporator). In some aircraft applications, the principal cooling plant can be entirely vapor cycle based. Given the transportation importance of environmental control, high reliability and availability of VCMs is needed to support transportation applications. For one example, in one aircraft application, an air cycle pack is augmented by a Supplemental Cooling System (SCS), a series of vapor cycle packs, that chill a coolant which is then circulated throughout the airplane. This coolant is used in food and beverage cooling for passenger service but also for cooling cabin and/or cargo recirculated air. The cooled recirculation air serves to cool the cabin and other areas of the airplane. As a result, the SCS function is highly important to airplane operations.
VCMs typically have component(s) providing a refrigerant filtration and drying function (FDF). These components normally have design life limitations and require maintenance repair or replacement as the unit accumulates operating hours or as the components become clogged. A failure in or wear out of FDF components may impact overall operation of the vapor cycle machine and in aircraft applications can also impact aircraft dispatch or operation. FDF components remove moisture and contaminants in refrigerant often generated by system wear or introduced in the system during manufacture or maintenance. Pressure loss increases and flow decreases typically with age and number of operating hours. Also, filter drier function life can decrease in severe conditions such as high cooling loads (hot air temperatures and high compressor speeds). If the filter wears (plugged or clogged), efficiency of the refrigeration system in typical designs, may be reduced or the system may need to be turned off. Loss of VCM air cooling capability on an aircraft may cause a flight to be delayed or cancelled.
Exemplary implementations of a filter dryer functions bypass system in a vapor cycle machine. The system includes a refrigerant filter/dryer receiving a flow of liquid refrigerant from an inlet line and expelling the liquid refrigerant to an outlet line. A bypass line interconnects the inlet line and the outlet line and a bypass valve is configured to divert a portion or all of the flow of liquid refrigerant from the inlet line into the bypass line. A condition sensor provides a condition status signal indicative of refrigerant filter dryer condition and the bypass valve is operable responsive to the condition status signal.
The implementations disclosed provide a method for operation of a vapor cycle machine. Condition of a refrigerant filter/dryer is sensed with a condition sensor. A condition status signal indicative of refrigerant filter/dryer condition is received from the condition sensor in a bypass controller. A bypass condition signal is issued from the bypass controller. A bypass valve is opened responsive to the bypass condition signal with the bypass valve configured to divert flow of liquid refrigerant from an inlet line inlet line of the refrigerant filter/dryer into a bypass line, the bypass line connected from the inlet line to an outlet line from the refrigerant filter/dryer.
The features, functions, and advantages that have been discussed can be achieved independently in various implementations or may be combined in yet other implementations further details of which can be seen with reference to the following description and drawings.
The ability to sustain vapor cycle machine (VCM) operation with failed or degraded FDF components (beyond a normal maintenance cycle) is valuable. For aircraft, this can enable continued aircraft operation until maintenance can be performed at a more convenient time or place. For example, simple reconfiguration could allow aircraft operations for a time period, such as 10 days, until an effective repair or VCM replacement can occur. In transportation use, FDF components commonly require the VCM to be evacuated of refrigerant. This and equipment/tooling requirements typically require that VCM service occur in a shop environment. The implementations disclosed herein are demonstrated in aircraft applications; however, the concept is adaptable to other applications where cooling is critical, when extended/continuous operation of VCMs are required, and/or when space, weight, cost, or other constraints limit VCM or VCM component sizes. VCMs can be used but not limited to refrigeration, cooling, or heat pump applications. It is noted that bypass of the FDF function can result in further machine wear and may result in additional component failures affecting affecting repair costs. This is deemed an acceptable trade for increased availability as component wear is a prevalent cause of FDF wear out or failure. The implementation described herein provide a bypass system having a bypass loop and valve on a that allows for continuous operation even during critical filter dryer end of life or failure conditions. The implementations disclosed allow the vapor cycle machine to still operate, preventing shut down of supported systems, such as air conditioning (HVAC) systems used in commercial or private settings, aircraft food refrigeration or cabin cooling, preventing or minimizing airplane flight delays or cancellation of flights, and spoilage of food and/or beverages. This can yield maintenance efficiencies, operational efficiencies, cost savings, and customer satisfaction. While described herein for use with aircraft systems, the implementations can be used not only in the aerospace industry, but also in home and industrial applications (vapor cycle refrigeration systems). The bypass system described herein can operate manually or automatically with electromechanical valve and control components.
Referring to the drawings,
In a first example implementation a bypass valve 30 is positioned in the bypass line 32 of bypass system 26 as shown in FIG.1. In this configuration, opening of the bypass valve 30 results in partial bypass of the flow of liquid refrigerant reducing the load on the refrigerant filter/dryer 18 but with continuing flow through the refrigerant filter/dryer unless the refrigerant filter dryer becomes fully plugged. In that condition, all flow is bypassed. Without bypass, a VCM commonly will be turned off due to excessive pressure when the FDF wears to the point of terminal pressure loss.
Details of a second example implementation of the bypass system 26 are seen in
Bypass valve 30 may be a manual valve which is operated by a mechanic or technician based on a requirement for a bypass condition. Alternatively, bypass valve 30 may be an automatic electromechanical valve operated by a solenoid upon receipt of an electrical bypass condition signal 38. A hydraulically operated valve may also be employed for either manual or automatic operation. The bypass valve 30 may reroute all or a portion of the flow from the inlet line 17 using, for example, a three port ball valve or a positionable stem and multiseat valve. As seen in
In example implementations, as shown in
The system interface 50 connected to the condition sensor 46 and employing lights or other displayed digital warnings (e.g. Filter /drier is 50% life, at 100% life, has 2 days remaining of by-pass operation) to provide indication to a user, such as a pilot, mechanic or automated maintenance monitoring system, of the operating condition of the refrigerant filter/dryer 18 responsive to the condition status signal 48. A position status signal 54 from the bypass valve 30 is provided to the system interface 50 and is displayed to indicate operation or position of the valve. In certain implementations, the position status signal provides feedback to the bypass controller 52.
In certain implementations, dynamic life extension of the refrigerant filter/dryer 18 is obtained by automated operation of the bypass valve 30. When the vapor cycle machine 10 is operating at conditions where moisture or particulate risks are low (low power, stable refrigerant) the refrigerant filter/dryer 18 is by-passed automatically through operation of bypass valve 30. When conditions change, full refrigerant filter/dryer function can be restored by positioning the bypass valve 30 for no bypass flow. This may serve to extend the life of the filter function of the filter/drier. Bypass function is determined and controlled by the bypass controller 52 by sensing states within the system (pressures, temperatures, compressor speeds, valve positions or through other parameters like number of operating hours since last service, output temperatures vs time, etc.) provided by the condition sensor 46 or other operational sensors in the vapor cycle system or aircraft.
The disclosed implementations enable continued operation of the vapor cycle machine 10 for a limited time period until repair of the refrigerant filter/dryer 18 can be scheduled and accomplished (e.g. like 10 day MEL in the Aviation Industry). In a transport application, a vehicle could be used and then ferried to a maintenance station at a convenient time. Performance during the time limited period of bypass operation, depending on original refrigerant filter/drier sizing, would only be degraded slightly. Additionally, with automated control and modulation of the bypass valve 30, enhanced benefits such as increased refrigerant filter/dryer longevity may be obtained. Some level of filtration can also be maintained up to the point of full by-pass. Controlled bypass, particularly with added FDF components in the bypass line, can maintain the vapor cycle machine 10 at FDF terminal characteristics (pressure drop) to minimize further systems degradation and maximum level of FDF function.
The implementations disclosed provide a method 400 for operation of a vapor cycle machine 10 as shown in
Having now described various implementations of the invention in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific implementations disclosed herein. Such modifications are within the scope and intent of the following claims. Within the claims the terms “comprising”, “including”, “having” and “containing” are intended to be open and additional or equivalent elements may be present. As used herein “and” and “or” are mutually inclusive unless otherwise limited.
