Cascade Heat Pump Compressor Selection for Maximum Efficiency
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Solution Overview
Problem
The complexity of managing a group of heat pumps with rotary compressors to achieve maximum efficiency is challenging due to their variable rotational frequency and power output, requiring complex selection and coordination of compressors to meet load demands efficiently.
Innovation Solution
A method for selecting and managing subgroups of rotary compressors based on their displacement and efficiency curves, using a common operating frequency to optimize power output and reduce compressor alternation, while incorporating conventional heat generators to supplement power when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If complex selection and coordination of compressors is used to meet load demands, then power output efficiency is improved, but system complexity increases
Solution Approach 1:
The system divides the group of compressors into multiple subgroups based on their efficiency characteristics and operating ranges. Each subgroup is managed independently with simplified control logic, avoiding the need for complex coordination of all compressors simultaneously. This segmentation allows efficient load distribution while maintaining manageable system complexity.
Solution Approach 2:
The patent utilizes the variable rotational frequency parameter of rotary compressors to optimize efficiency. By dynamically adjusting the operating frequency of compressors within subgroups based on load demands, the system achieves high efficiency without requiring complex mechanical modifications or additional control mechanisms.
2Adaptability or versatility
If compressor rotational frequency is highly variable to adapt to power requirements, then adaptability is improved, but efficiency is reduced
Solution Approach 1:
The system dynamically adjusts the rotational frequency of compressors within optimized ranges based on real-time load conditions. By implementing dynamic frequency modulation rather than fixed-speed operation, the system maintains high efficiency across varying power requirements while preserving adaptability to different operating conditions.
Solution Approach 2:
Multiple compressors are merged into coordinated subgroups that operate together to meet load demands. This combining allows the system to achieve high adaptability through collective operation while maintaining efficiency by ensuring each compressor operates within its optimal frequency range.
3Use of energy by moving object
If frequent alternation of compressors is implemented to maintain efficiency, then energy efficiency is improved, but system reliability decreases
Solution Approach 1:
Compressors are pre-configured into subgroups based on their efficiency characteristics and operating ranges before operation begins. This preliminary organization allows the system to maintain efficiency by switching between pre-optimized subgroups rather than frequently individual compressors, thereby reducing the frequency of alternation and improving system reliability.
4Reliability
If conventional heat generators are added to supplement power, then power delivery reliability is improved, but system complexity increases
Solution Approach 1:
The system integrates conventional heat generators as multi-functional components that can operate independently or in coordination with the heat pump compressors. This universal approach allows the same infrastructure to serve both as supplemental heating and as a backup power source, improving reliability without proportionally increasing system 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
This approach simplifies the selection process, maintains high efficiency by operating compressors close to their maximum efficiency frequency, and ensures reliable power delivery by coordinating compressor operation and supplementary heat sources.
Implementation Method 1
the refrigeration machines apply the refrigerant fluid compression refrigeration cycle and use rotary compressors of a suitable type to operate at highly variable rotational frequency
Implementation Method 2
a group of heat pumps with rotary compressors to achieve maximum efficiency... intended to the refrigeration and heating of a common heat transfer fluid
Data Source
Figure 1~3
Figure 2
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AI summary
In a system (S.HP) comprising a group of refrigeration machines (HP) equipped with a group (Gm) of m rotary compressors (Cp), for meeting the thermal load W.req.(t) of a utility (UT) with the maximum possible efficiency, there is described a method for the selection of the rotary compressors (Cp) to be activated at the moment (t) to provide said thermal load W.req.(t) For each generic k-th compressor of the m compressors (Cp) a ratio is defined Opt.output.power.k = W.max.eff.k / W.max.k where W.max.eff.k is the power that may be output at maximum efficiency at a frequency FR.max.Eff.k and W.max.k is the maximum power output at the maximum frequency FR.max.oper.k. According to the invention it is assumed that: a) each of said compressors (Cp) has a ratio Opt.output.power of equal value and required at the same frequency FR.max.Eff; b) each of said compressors (Cp) and possible subgroups (Gn) of n compressors (Cp) outputs a maximum power proportional to the respective displacement according to a same ratio R.W.cc; c) the displacement cc.rif corresponding to a maximum power equal to said thermal load W.req.(t); d) activates, in order to provide said thermal load W.req.(t), the subgroup (Gn) for which the ratio Gn.cc/cc.rif is closest to said valueOpt.output.power; e) possibly replaces some compressor (Cp) of the subgroup (Gn) chosen with other compressors that better meet other secondary conditions.