Ejector Refrigeration Cycle Bypass Control for Stable COP
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Solution Overview
Problem
Existing refrigeration cycle apparatuses with ejectors suffer from reduced expansion power due to pressure reduction by variable throttle mechanisms, leading to inefficient operation, especially when refrigerant flow passage areas become excessively small with increased cooling load, deviating from optimal operating states.
Innovation Solution
A refrigeration cycle apparatus with a bypass circuit and flow control valves that adjust refrigerant flow rates to maintain optimal operating conditions, including a first refrigerant path with a compressor, radiator, and evaporator, a second path with a compressor and second evaporator, a third path branching to the ejector's driving inlet, and a bypass connecting the ejector's mixed refrigerant outlet to the second evaporator, controlled by flow control units to manage refrigerant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a variable throttle mechanism is mounted at the outlet of the condenser to control refrigerant flow, then the refrigerant flow rate can be adjusted according to cooling load, but the pressure of the refrigerant flowing into the ejector is reduced, reducing expansion power collected by the ejector
Solution Approach 1:
The refrigerant flow control is segmented into two independent paths: one path through the ejector for expansion power collection, and another path through the variable throttle mechanism for cooling capacity control. This segmentation allows each path to optimize its function independently without interfering with the other.
Solution Approach 2:
A three-way valve is introduced as an intermediary device to distribute refrigerant between the ejector path and the variable throttle path. This mediator allows flexible control of refrigerant distribution to balance expansion power and cooling capacity requirements under different operating conditions.
2Power
If the flow passage area of the nozzle portion and fixed throttle is set to maximize expansion power collection, then the ejector efficiency is optimized at design conditions, but when cooling load increases and refrigerant circulation is increased, the flow passage areas become excessively small, causing operation to deviate from optimal state
Solution Approach 1:
The system transitions from fixed flow passage areas to dynamic flow control by introducing variable throttle mechanisms and three-way valves that can adjust refrigerant distribution in real-time. This allows the system to adapt to varying cooling loads while maintaining optimal ejector operation.
Solution Approach 2:
The refrigerant flow rate and distribution parameters are made variable through control mechanisms. By changing the opening degree of three-way valves and variable throttle mechanisms, the system can adjust the refrigerant flow passage area dynamically to match different cooling load conditions, preventing excessive small flow areas at high loads.
3Ease of manufacture
If fixed flow passage areas are used in the ejector to simplify the structure, then manufacturing is easier and device complexity is reduced, but the system cannot adapt to varying cooling loads and maintains optimal operation only at design conditions
Solution Approach 1:
The ejector is designed with multi-functionality: it serves both as an expansion device for power collection and as part of a controllable refrigerant distribution system. The three-way valves and variable throttle mechanisms add universal control capability that serves both simple operation and adaptive performance functions.
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 the operating efficiency of the refrigeration cycle by stabilizing refrigerant flow ratios and pressures, maintaining high COP even when cooling loads vary, thereby improving energy efficiency and operational stability.
Implementation Method 1
an ejector having a driving refrigerant inlet into which a driving refrigerant flows, a suction refrigerant inlet into which a suction refrigerant flows, and a mixed refrigerant outlet through which a mixed refrigerant which is a mixture of the driving refrigerant and the suction refrigerant flows out
Data Source
AI summary
In a refrigeration cycle apparatus, a compressor, a condenser, a first flow control valve, a refrigerant storage container, a second flow control valve, and a first evaporator are connected in this order, and a third flow control valve, an ejector, a second evaporator, and the compressor are connected in this order so as to branch from an outlet of the condenser. A driving refrigerant inlet of the ejector is connected to the third flow control valve, a suction refrigerant inlet of the ejector is connected to an outlet of the first evaporator, and a mixed refrigerant outlet of the ejector is connected to a refrigerant inlet of the second evaporator. The refrigeration cycle apparatus has a bypass circuit which branches from a refrigerant pipe connecting the condenser and the second flow control valve and is connected to the mixed refrigerant outlet of the ejector via a fourth flow control valve.