Multi-Indoor Refrigeration Control for Lower Compressor Power
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Solution Overview
Problem
Conventional multi-type refrigeration systems do not optimize compressor power consumption when adjusting heat exchange in indoor units, leading to increased power consumption and decreased coefficient of performance (COP).
Innovation Solution
A refrigeration system with a variable capacity compressor and adjustable expansion mechanisms, where the set temperature is increased when the minimum target superheat degree is higher than a predetermined value, reducing compressor capacity and adjusting pressure reduction to maintain heat exchange, thereby reducing power consumption and preserving COP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If compressor capacity control and refrigerant outlet superheat degree control are performed using conventional methods, then the indoor temperature can approach the set temperature, but the compressor power consumption increases and the coefficient of performance decreases
Solution Approach 1:
The invention changes the control parameters from independent compressor capacity control and expansion valve control to integrated control based on refrigerant outlet superheat degree and evaporation temperature. By monitoring the superheat degree at the evaporator outlet and the evaporation temperature at the compressor suction side, the system dynamically adjusts the expansion valve opening and compressor capacity to maintain optimal operating conditions, thereby reducing power consumption while achieving temperature control.
Solution Approach 2:
The system implements feedback control by continuously measuring the refrigerant outlet temperature and pressure at the evaporator, calculating the superheat degree, and using this information to adjust the expansion valve opening. Additionally, the evaporation temperature is measured at the compressor suction side to feedback control the compressor capacity, creating a closed-loop control system that optimizes energy efficiency.
2Temperature
If the compressor capacity is increased to maintain heat exchange when evaporation temperature is lower than set temperature, then the evaporation temperature approaches the set temperature, but the power consumption of the compressor increases
Solution Approach 1:
The invention changes the control approach by using evaporation temperature feedback to dynamically adjust compressor capacity. Instead of operating at fixed capacity, the compressor capacity is modulated based on the actual evaporation temperature measured at the suction side, allowing the system to use only the necessary capacity to maintain the required evaporation temperature, thus reducing unnecessary power consumption.
3Temperature
If the expansion valve opening is adjusted to control refrigerant flow and heat exchange, then the refrigerant outlet superheat degree can reach target values, but the system cannot optimize compressor power consumption
Solution Approach 1:
The system uses feedback control where the refrigerant outlet temperature and pressure are continuously measured, the superheat degree is calculated, and this information is fed back to adjust the expansion valve opening. This ensures the superheat degree remains within optimal ranges while coordinating with compressor capacity control to minimize overall system power consumption.
Solution Approach 2:
The invention dynamically changes the expansion valve opening degree based on real-time superheat degree measurements and cooling load requirements. By coordinating the expansion valve adjustment with compressor capacity control, the system optimizes refrigerant flow to match actual demand, preventing both over-expansion (which wastes energy) and under-expansion (which reduces efficiency).
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 approach reduces compressor power consumption and maintains heat exchange levels, enhancing the refrigeration system's COP by adjusting the set temperature and pressure reduction in response to operating conditions.
Implementation Method 1
an compressor 21 having a variable capacity
Implementation Method 2
an amount of pressure reduction of a refrigerant passing through each of the expansion mechanisms 26
Implementation Method 3
a plurality of evaporators 27... an amount of heat exchange necessary for the evaporators 27
Data Source
AI summary
An air conditioner (10) includes a refrigerant circuit (20) including a plurality of indoor heat exchangers (27). A controller (1) for controlling operation of the air conditioner (10) includes a change unit (5) configured to change a set temperature Tem to a value larger than a current value when the minimum target superheat degree SHsm of target superheat degrees SHs determined for the respective indoor heat exchangers (27) is higher than a predetermined value SHt.