Variable-Speed Compressor Control for Process Cooling Energy Reduction
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Solution Overview
Problem
Existing refrigeration units lack efficient control over cooling capacity, leading to high energy consumption, heat emission, and noise due to constant compressor speed and limited valve control, especially in bathroom appliances with temperature-controlled liquid baths.
Innovation Solution
A process cooling unit with a variable-speed compressor and a control device using a characteristic map to adjust compressor speed and injection valve based on process parameters, allowing for precise control of cooling capacity without additional valves like hot gas valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant-speed compressor is used, then the device complexity is reduced, but energy consumption increases
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant-speed compressor to a dynamic variable-speed compressor. The compressor motor speed is continuously adjusted based on the actual cooling demand and operating conditions, allowing the system to adapt its performance to match the load requirements, thereby reducing energy consumption while maintaining simple control architecture.
Solution Approach 2:
The patent changes the operational parameters of the compressor by varying its speed rather than maintaining a fixed speed. The control device adjusts the compressor speed parameter according to the cooling load, enabling energy savings of over 60% in partial load operations while avoiding the need for complex multi-valve control systems.
2Productivity
If injection valve throttling is used to reduce cooling capacity, then cooling output is reduced, but energy consumption increases
Solution Approach 1:
Instead of using static valve throttling to reduce cooling capacity, the patent dynamically adjusts the compressor speed to match the required cooling output. This dynamic approach allows the system to reduce both cooling capacity and energy consumption simultaneously, achieving over 60% energy savings in partial load operations without the energy penalties associated with valve throttling.
3Productivity
If hot gas valve is added to reduce output, then cooling capacity is reduced, but heat dissipation into room increases
Solution Approach 1:
The patent extracts the hot gas valve component from the system entirely. By using variable-speed compressor control, the system achieves cooling capacity reduction without needing the hot gas valve, thereby eliminating the associated heat dissipation into the room and the added device complexity.
4Ease of operation
If multiple controllable valves are installed, then device complexity increases, but control precision improves
Solution Approach 1:
The patent removes the hot gas valve from the system, simplifying the valve architecture. Cooling capacity control is achieved through variable-speed compressor control rather than multiple valves, reducing device complexity while maintaining precise control through the characteristic map-based control algorithm.
Solution Approach 2:
The patent replaces the mechanical multi-valve control system with an electronic control system that adjusts compressor speed. The control device uses a characteristic map stored in memory to determine optimal compressor speed based on process parameters, providing precise control without the mechanical complexity of multiple controllable valves.
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 reduces energy consumption by over 60% in partial load operations, minimizes heat emission, lowers operating noise, and enables smaller designs by allowing the compressor to operate at reduced speeds, eliminating the need for hot gas valves and reducing compressor wear.
Implementation Method 1
a compressor (175) with a variable-speed motor
Implementation Method 2
an evaporator (125) with an injection valve
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
Process cooling unit (100), comprising: an evaporator (125) with an injection valve, a compressor (175) with a variable speed motor, a speed control device for controlling the speed of the motor, and a control device which includes a memory in which a characteristic map is stored, and wherein the control device is configured to control the speed of the motor of the compressor as a function of at least one process parameter of a cooling process of the process cooling unit (100) and as a function of the characteristic map.