Expansion unit for installation in a refrigerant circuit
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Solution Overview
Problem
Refrigerant circuits with expansion units face inefficiencies due to the need for throttle elements to adjust mass flow, which limits energy recovery and optimal supercooling.
Innovation Solution
A refrigerant circuit with a mechanically functional coupling between the expander and compressor stages, utilizing an electrically drivable servomotor to control the supercooling mass flow, ensuring maximum energy recovery and optimal supercooling without throttle elements, and incorporating a branching system for pre-cooling and countercurrent heat exchanger design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a throttle element is used to adjust mass flow to the expander stage, then mass flow regulation is achieved, but energy recovery is limited and device complexity increases
Solution Approach 1:
The patent removes the throttle element from the system entirely. Instead of using a throttle valve to regulate mass flow to the expander stage, the system directly supplies mass flow from the condenser to the expander, eliminating the energy loss associated with throttling while reducing device complexity.
Solution Approach 2:
The patent changes the operating parameters by operating the expander at variable speed to match the mass flow requirements. Instead of regulating flow through a throttle, the system adjusts the expander's rotational speed to accommodate varying mass flow rates, thereby maximizing energy recovery without requiring additional flow control components.
2Temperature
If a throttle element is used to regulate mass flow, then flow control is achieved, but optimal supercooling cannot be realized
Solution Approach 1:
The patent eliminates the throttle element that prevented optimal supercooling. By removing the restriction caused by the throttle valve, the system allows the refrigerant to achieve maximum supercooling in the condenser, improving temperature control and heat transfer efficiency.
Solution Approach 2:
The patent implements dynamic control of the expander speed to match varying mass flow requirements. This dynamic adjustment allows the system to maintain optimal supercooling conditions across different operating points, as the expander can adapt its speed to process the supercooled refrigerant efficiently without the constraints of a fixed-flow throttle element.
3Loss of energy
If the expander and compressor stages are mechanically coupled, then energy generated in expander is directly transferred to compressor, but control of mass flow becomes more challenging
Solution Approach 1:
The patent replaces complex mechanical flow control mechanisms with electrical control of the expander motor. The mechanically coupled expander-compressor system uses an electrically driven expander with variable speed control, allowing precise adjustment of mass flow to the expander stage through electrical parameters rather than mechanical throttling, thereby maintaining ease of operation while achieving direct energy transfer.
4Loss of energy
If no throttle element is provided, then energy recovery is maximized, but mass flow regulation capability is reduced
Solution Approach 1:
The patent changes the control parameter from mechanical flow restriction to electrical speed control. By eliminating the throttle element and using an electrically driven expander with variable speed capability, the system maximizes energy recovery while maintaining adaptability through electronic control of the expander's rotational speed to match varying mass flow requirements.
Solution Approach 2:
The patent implements a dynamic control system where the expander speed is continuously adjusted to match the mass flow supplied from the condenser. This dynamic speed regulation provides the necessary mass flow control capability without requiring a static throttle element, thereby maximizing energy recovery while maintaining system versatility across different operating conditions.
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
This configuration enhances energy efficiency by eliminating throttle elements, achieving maximum energy recovery and optimal supercooling, while damping pulsations and allowing for greater subcooling, especially in subcritical heat removal scenarios.
Implementation Method 1
the mass flow expanded by the expander stage
Implementation Method 2
the subcooling mass flow, which is compressed by the compressor stage
Implementation Method 3
the subcooling unit being designed as a heat exchanger unit and cooling the refrigerant mass flow to the expander stage by the subcooling mass flow passing through it in counterflow
Implementation Method 4
the expansion device includes an electrically driven actuator
Data Source
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AI summary
The invention relates to an expansion unit for installation in a refrigerant circuit comprising an expansion system having: a supercooling unit for supercooling a mass flow of a refrigerant fed to the expansion unit; an expansion-compression unit comprising an expander stage and a compressor stage; a branch which separates off a supercooling mass flow from a total mass flow fed to the expansion unit and is connected to a feed line which conducts the supercooling mass flow to an input of the supercooling unit; an expansion member which expands the supercooling mass flow to a supercooling pressure; a connecting line which feeds the supercooling mass flow exiting from the supercooling unit to the compression stage which for its part compresses the supercooling mass flow to a high return pressure; and an electrically operating controller which senses an ambient temperature and/or a temperature of the mass flow of the refrigerant fed to the expansion unit and/or to the expander stage and, in accordance with this temperature, sets an input pressure of the expansion unit or of the expansion-compression unit by controlling the supercooling mass flow by means of the expansion member actuated electrically by the controller.