Ejector refrigeration circuit
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Solution Overview
Problem
Ejector refrigeration circuits face efficiency degradation when the pressure difference between the high and low pressure inlets and outlets is low, leading to reduced performance.
Innovation Solution
Incorporating a liquid pump outside the receiver and a bypass line with a switchable valve to adjust refrigerant flow, allowing the liquid pump to increase pressure and bypass non-operational stages to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure difference between high pressure inlet and outlet of the ejector is low, then the ejector efficiency decreases, but the refrigeration circuit cannot operate at low pressure differences without additional components
Solution Approach 1:
A liquid pump is introduced as an intermediary component between the receiver and the evaporator to actively increase the pressure of liquid refrigerant. This mediator enables the system to overcome low pressure differences that would otherwise reduce ejector efficiency, allowing operation across a broader pressure range while maintaining reliable ejector performance.
Solution Approach 2:
The system transitions from a passive pressure-dependent ejector operation to an active dynamic pressure control system. The liquid pump dynamically adjusts refrigerant pressure in the evaporator circuit, enabling the ejector to maintain high efficiency across varying operating conditions and pressure differences.
2Volume of stationary object
If the liquid pump is located inside the receiver, then the system is more compact, but the ease of maintenance and replacement deteriorates
Solution Approach 1:
The liquid pump is extracted from the receiver and positioned as a separate external component. This separation maintains the compact integrated design of the refrigeration circuit while providing easy accessibility to the pump for maintenance, replacement, and servicing without requiring disassembly of the receiver.
3Productivity
If the liquid pump is added to increase pressure in the evaporator circuit, then the refrigeration capacity improves, but the device complexity increases
Solution Approach 1:
The liquid pump serves multiple functions: it increases refrigerant pressure to improve ejector efficiency, enables operation at low pressure differences, and can be controlled to optimize refrigeration capacity across different operating conditions. This multi-functionality justifies the additional component by providing several benefits simultaneously.
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 the refrigeration circuit's efficiency by increasing pressure within the evaporator circuit and reducing pressure drops, improving refrigeration capacity and ease of maintenance.
Implementation Method 1
a liquid pump having an inlet side, which is fluidly connected to the liquid outlet of the receiver, and an outlet side
Implementation Method 2
an ejector expands the refrigerant radiating heat in the condenser, sucks the refrigerant evaporated in the evaporator, recovers a pressure of the refrigerant by converting expansion energy into pressure energy
Implementation Method 3
A condenser cools the refrigerant compressed by the compressor by heat radiation
Implementation Method 4
at least one refrigeration expansion device having an inlet side, which is fluidly connected to the outlet side of the liquid pump, and an outlet side
Data Source
Figure 1
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AI summary
An ejector refrigeration circuit (1) comprises: a high pressure ejector circuit (3) comprising in the direction of flow of a circulating refrigerant: a heat rejecting heat exchanger/gas cooler (4) having an inlet side (4a) and an outlet side (4b); at least one ejector (6) comprising a primary high pressure input port (6a), a secondary low pressure input port (6b), and an output port (6c), the primary high pressure input port (6a) being fluidly connected to the outlet side (4b) of the heat rejecting heat exchanger/gas cooler (4); a receiver (8), having a liquid outlet (8c), a gas outlet (8b) and an inlet (8a), which is fluidly connected to the output port (6c) of the at least one ejector (6); at least one compressor (2a, 2b, 2c) having an inlet side (21a, 21b, 21c) and an outlet side (22a, 22b, 22c), the inlet side (21a, 21b, 21c) of the at least one compressor (2a, 2b, 2c) being fluidly connected to gas outlet (8b) of the receiver (8) and the outlet side (22a, 22b, 22c) of the at least one compressor (2a, 2b, 2c) being fluidly connected to the inlet side (4a) of the heat rejecting heat exchanger/gas cooler (4); and a refrigerating evaporator flowpath (5) comprising in the direction of flow of the circulating refrigerant: a liquid pump (7) having an inlet side (7a), which is fluidly connected to the liquid outlet (8c) of the receiver (8), and an outlet side (7b); at least one refrigeration expansion device (10) having an inlet side (10a), which is fluidly connected to the outlet side (7) of the liquid pump (7), and outlet side (10b); and at least one refrigeration evaporator (12) fluidly connected between the outlet side (10b) of the at least one refrigeration expansion device (10) and the secondary low pressure input port (6b) of the at least one ejector (6). The liquid pump (7) is located outside the receiver (8) and/or the liquid pump (7) comprises a bypass-line (11 ) including a switchable bypass valve (15) allowing refrigerant to selectively bypass the liquid pump (7) by opening the switchable bypass valve (15).