Brayton cycle type refrigerating apparatus
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Solution Overview
Problem
In refrigerating apparatus using a Brayton cycle with multiple stages of compressors, controlling refrigeration capacity in response to changes in heat load is slow and inefficient, leading to reduced coefficient of performance due to changes in rotational speed, which affects adiabatic efficiency and other control parameters.
Innovation Solution
A Brayton cycle type refrigerating apparatus with a heat load detecting device, buffer tank, and valve control system that adjusts refrigerant flow rate without changing pressure ratio or temperature, using a control device to manage the opening degrees of valves on the buffer tank to control refrigerant flow, thereby maintaining efficiency and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rotational speed control is used to adjust refrigeration capacity, then refrigeration capacity can be adjusted to heat load, but response time becomes slow and coefficient of performance decreases
Solution Approach 1:
The patent changes the control parameter from rotational speed to refrigerant flow rate. By controlling the flow rate of refrigerant through valve adjustment rather than changing compressor/expander rotational speeds, the system achieves rapid response to heat load changes while maintaining stable operating conditions that preserve coefficient of performance and adiabatic efficiency.
2Adaptability or versatility
If rotational speed is changed to control refrigeration capacity, then capacity control is achieved, but adiabatic efficiency of expander decreases and COP is reduced
Solution Approach 1:
The patent changes the control parameter from rotational speed to refrigerant flow rate. By adjusting the flow rate of refrigerant through valve control while maintaining constant rotational speeds of compressors and expanders, the system achieves capacity control without compromising adiabatic efficiency or energy consumption.
3Power
If multiple stages of compressors are used to improve cooling capacity, then cooling capacity increases, but number of control parameters increases and response becomes slower
Solution Approach 1:
The patent applies a universal control approach where a single control parameter (refrigerant flow rate) is used to control the entire multi-stage compression system. Instead of independently controlling each compressor stage, the system uses flow rate control that affects all stages uniformly, simplifying the control structure while maintaining the enhanced cooling capacity provided by multiple compressor stages.
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 solution allows for rapid adjustment of refrigeration capacity in response to heat load changes without reducing adiabatic efficiency or coefficient of performance, achieving excellent energy efficiency and responsiveness without the need for external power supply.
Implementation Method 1
a buffer tank provided between a low pressure line in which the refrigerant before being compressed by the compressors flows and a high pressure line in which the refrigerant after being compressed by the compressors flows
Implementation Method 2
multiple stages of compressors arranged in series on a refrigerant line for generating cool heat by using a refrigerant compressed by the compressors
Implementation Method 3
Brayton cycle type refrigerating apparatus which is capable of controlling the cooling capacity against a change in heat load of the object to be cooled
Data Source
AI summary
A Brayton cycle type refrigerating apparatus using multiple stages of compressors and having a good response without reduction in efficiency due to change in heat load of the object to be cooled is provided. The Brayton cycle type refrigerating apparatus includes on a refrigerant line on which multiple stages of compressors are arranged in series. The apparatus also includes a temperature sensor for detecting heat load of an object to be cooled and a buffer tank provided between a low pressure line and a high pressure line. A flow rate of the refrigerant in the refrigerant line is controlled by controlling opening degrees of valves to adjust the cooling capacity.