Method of flow control for low ambient heat pump using wet injection circuit
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Solution Overview
Problem
Heat pumps face challenges in efficiently transporting heat across large temperature gradients, particularly in low ambient temperatures, leading to inefficiencies and reduced compressor performance in residential applications.
Innovation Solution
A climate control system with a wet-injection bypass line that routes refrigerant from the main refrigerant circuit between heat exchangers to the compressor inlet, controlled by a controller that adjusts flow rate based on parameters such as evaporator and condenser saturation temperatures and outdoor ambient temperature, using capillary tubes or electronic expansion valves to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat pump operates in low ambient temperature conditions, then heating capability is maintained, but compressor efficiency deteriorates and operating range is limited
Solution Approach 1:
A bypass line is introduced as an intermediary refrigerant flow path that connects the discharge side to the suction side of the compressor. This bypass line includes a flow control valve that mediates the refrigerant flow to optimize compressor performance by adjusting the amount of refrigerant circulating through the bypass, thereby maintaining reliable operation in low ambient temperature conditions
Solution Approach 2:
The system changes the refrigerant flow parameters by dynamically adjusting the bypass valve opening based on operating conditions. By modifying the refrigerant flow rate through the bypass line, the system optimizes compressor suction pressure and temperature parameters, extending the operating range and maintaining efficiency across varying ambient temperatures
2Productivity
If complex control systems are used to improve heat transport efficiency, then performance improves, but device complexity increases
Solution Approach 1:
The bypass flow control valve operates based on inherent system feedback where the refrigerant flow automatically balances between the main circuit and bypass line. The system self-regulates by utilizing the pressure and temperature differences that naturally occur during operation, eliminating the need for complex external control mechanisms while maintaining high heat transport efficiency
3Temperature
If supplemental heating methods are added to address low temperature performance, then heating capability improves, but device complexity and cost increase
Solution Approach 1:
The bypass line serves multiple functions: it acts as a refrigerant recirculation path to maintain compressor suction pressure, provides cooling to the compressor during high ambient temperature operation, and extends the low-temperature heating capability. This multi-functional design eliminates the need for separate supplemental heating components, reducing overall system complexity while maintaining heating capability across a wide temperature range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances compressor efficiency and extends the operating range of the heat pump by optimizing refrigerant flow, improving performance and reducing compressor stress in cold climates.
Implementation Method 1
circulating refrigerant fluid through a main refrigeration circuit to satisfy a conditioning load
Implementation Method 2
determining a first parameter of the refrigerant fluid proximate the evaporator heat exchanger and a second parameter of the refrigerant fluid proximate the condensing heat exchanger
Implementation Method 3
adjusting a position of a valve coupled to the wet-injection bypass line in response to determining the period of time is over a threshold period of time and the outdoor ambient temperature is below the temperature threshold
Implementation Method 4
the wet-injection bypass line includes a plurality of capillary tube circuits routed in parallel, each of the plurality of capillary tube circuits including a solenoid valve and a capillary tube
Data Source
AI summary
A method and apparatus for controlling a climate control system with a wet injection bypass line during heating mode for maintaining efficient operating temperatures and compressor ratio of a compressor at low ambient temperature. The process may include selectively routing a portion of a refrigerant through a wet-injection bypass line and controlling a flow rate of the portion of refrigerant flow through the wet-injection bypass line. Controlling the flow rate of the refrigerant flowing through the bypass line includes adjusting a valve or valves coupled the at least one wet-injection bypass line or multiple wet-injection bypass lines based on measured parameters of the refrigerant fluid, outdoor conditions, indoor conditions, and the operating map for the compressor.