Ejector Refrigeration Flow Distribution for Varying Heat Loads
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Solution Overview
Problem
Vapor compression refrigerating cycle apparatuses face challenges in improving the coefficient of performance (COP) due to changes in heat load, which reduce nozzle efficiency and pressure increase by the ejector, especially in varying load conditions.
Innovation Solution
Incorporating a flow distributor that adjusts the ratio of refrigerant flow rates through different passages to optimize the dryness of the refrigerant, ensuring appropriate pressure increase by the ejector across different load conditions, thereby maintaining efficiency and improving COP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigerant is in a gas and liquid two-phase condition at the inlet of the nozzle portion, then the refrigerating cycle can operate under varying heat loads, but the pressure energy input to the ejector is reduced and nozzle efficiency decreases
Solution Approach 1:
The refrigerant flow is divided into two separate passages: a liquid-phase refrigerant passage and a gas-phase refrigerant passage. This segmentation allows each passage to handle refrigerant in its optimal phase state, ensuring that the nozzle receives high-quality liquid refrigerant for efficient expansion while the gas-phase refrigerant is handled separately, thus resolving the contradiction between adaptability to varying heat loads and maintaining nozzle efficiency.
Solution Approach 2:
Different passages are provided for different phases of refrigerant (liquid and gas), giving each passage specialized quality suited to its function. The liquid-phase passage optimizes for nozzle feed quality, while the gas-phase passage handles vapor refrigerant separately. This local quality differentiation maintains high nozzle efficiency across varying heat load conditions.
2Loss of energy
If a flow distributor is added to adjust refrigerant flow ratios, then ejector efficiency and COP are improved, but the device complexity increases
Solution Approach 1:
The flow distributor is integrated with the existing refrigerant distribution system, merging the flow adjustment function into the current architecture. The distributor uses the pressure differential naturally present in the system to automatically regulate flow ratios between liquid and gas passages, eliminating the need for external actuators or complex control mechanisms, thus improving ejector efficiency while minimizing added complexity.
Solution Approach 2:
The flow distributor operates autonomously by utilizing the pressure differential between the liquid and gas refrigerant lines to automatically adjust flow ratios. No external power source, control system, or actuation mechanism is required—the system self-regulates based on its own operating conditions, thereby improving ejector efficiency without significantly increasing device complexity.
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
The solution effectively adjusts refrigerant flow to enhance ejector efficiency and ensure pressure increase, leading to improved COP even in low and high load conditions, maintaining performance across varying heat loads.
Implementation Method 1
The ejector has a nozzle portion that converts pressure energy of the refrigerant flowing out from the radiator into velocity energy, thereby to isoentropically decompress and expand the refrigerant
Implementation Method 2
the ejector draws gas-phase refrigerant from in an evaporator by means of a high-velocity jet flow of refrigerant from the nozzle portion
Implementation Method 3
converts the velocity energy into pressure energy through a diffuser while mixing the drawn refrigerant with the refrigerant jetted from the nozzle portion
Data Source
AI summary
A vapor compression refrigerating cycle apparatus includes a compressor, a radiator, first and second throttle devices, a flow distributor, an ejector, a suction passage, and first and second evaporators. The flow distributor separates refrigerant decompressed through the first throttle device into a first passage and a second passage. The first passage is in communication with a nozzle portion of the ejector. The second passage is in communication with a suction portion of the ejector through the suction passage. The second throttle device and the second evaporator are disposed on the suction passage. The flow distributor is configured to be capable of adjusting a ratio of a flow rate of refrigerant passing through the second passage to a flow rate of refrigerant passing through the first passage in accordance with a heat load of at least one of the radiator, the first evaporator and the second evaporator.