Transcritical refrigeration system and associated method of operating the same.
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Solution Overview
Problem
Conventional refrigeration systems maintain constant flash tank pressure, which can lead to inefficiencies in energy usage and compressor operation, particularly in transcritical systems with ejectors, as they do not dynamically adjust based on gas cooler outlet temperature.
Innovation Solution
The pressure of the flash tank is dynamically adjusted based on the gas cooler outlet temperature to enhance the efficiency of the ejector and reduce energy usage associated with parallel compression, allowing for optimized operation of both parallel compressors and ejectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flash tank pressure is kept constant all the time, then system operation is simple and stable, but ejector efficiency is reduced and energy usage increases
Solution Approach 1:
The patent applies dynamics by transitioning from constant flash tank pressure to dynamic pressure adjustment based on gas cooler outlet temperature. The controller continuously monitors temperature and adjusts pressure setpoints accordingly, allowing the system to adapt to varying operating conditions and optimize ejector efficiency while maintaining stability through controlled variation rather than rigid constancy.
Solution Approach 2:
The patent implements parameter changes by adjusting the flash tank pressure setpoint as a function of gas cooler outlet temperature. When temperature exceeds a threshold, the pressure setpoint is modified to improve ejector performance. This dynamic parameter adjustment resolves the contradiction by allowing the system to maintain reliability through controlled changes while reducing energy consumption through optimized operating conditions.
2Productivity
If flash tank pressure is increased to improve ejector efficiency, then ejector performance improves, but parallel compression energy usage increases
Solution Approach 1:
The patent uses dynamics to adjust flash tank pressure based on real-time temperature conditions rather than maintaining a fixed high pressure. By dynamically modulating pressure in response to gas cooler outlet temperature, the system optimizes ejector efficiency only when necessary, thereby reducing unnecessary energy consumption during parallel compression operations.
Solution Approach 2:
The patent applies parameter changes by establishing a temperature-dependent pressure setpoint strategy. The flash tank pressure setpoint is increased only when gas cooler outlet temperature exceeds a predetermined threshold, and decreased when temperature is within acceptable ranges. This conditional parameter adjustment improves ejector efficiency during high-temperature operation while minimizing energy usage during normal conditions.
Data Source
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AI summary
In certain embodiments, a transcritical refrigeration system (100) provides refrigeration by circulating carbon dioxide (CO2) refrigerant through the system (100). A flash tank (105) of the transcritical refrigeration system (100) is operable to supply the CO2 refrigerant, in liquid form, to a low temperature refrigeration case (115a) and a medium temperature refrigeration case (115b). A low temperature compressor (120a) is operable to compress the CO2 refrigerant discharged from the low temperature refrigeration case (115a). A medium temperature compressor (120b), a parallel compressor (120c), and an ejector are each operable to compress the CO2 refrigerant discharged from the medium temperature refrigeration case (115b), the CO2 refrigerant discharged from the low temperature compressor (120a), and/or CO2 flash gas discharged from the flash tank (105). A gas cooler (130) is operable to cool the CO2 refrigerant discharged from the medium temperature compressor (120b) and the parallel compressor (120c). A controller (100) is operable to dynamically adjust a pressure set point for the flash tank (105).