Heat storage system
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Solution Overview
Problem
The energy consumption efficiency of heat accumulating operations in heat pump systems decreases due to low temperatures of the compressor and heat exchanger at the start, leading to increased amounts of low-temperature hot water flowing into the storage tank, which reduces overall efficiency.
Innovation Solution
A heat storage system with a compressor, heat storage tank, and heat exchange means, including a control mechanism that initially maintains a lower compressor frequency and subsequently increases it to a higher frequency to manage water flow rates and temperatures, reducing the accumulation of medium-temperature water and thus maintaining energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor operates at high frequency from the start of heat accumulating operation, then the heating efficiency is improved, but the compressor and heat exchanger temperatures become excessively high causing system instability
Solution Approach 1:
The compressor operating frequency is dynamically adjusted in two stages: initially maintained at a lower frequency to allow temperature stabilization, then increased to a higher frequency for efficient heating. This dynamic frequency adjustment resolves the contradiction between heating efficiency and system stability.
Solution Approach 2:
Before entering high-frequency heating operation, the compressor operates at a lower frequency to preliminarily stabilize the temperatures of the compressor and heat exchanger. This preliminary temperature stabilization prevents thermal shock and system instability when high-frequency operation begins.
2Reliability
If the compressor operates at low frequency at the start of heat accumulating operation, then the system stability is maintained, but the amount of low-temperature hot water increases reducing energy efficiency
Solution Approach 1:
The compressor frequency transitions dynamically from a lower initial frequency to a higher operating frequency. This dynamic adjustment allows the system to maintain stability during temperature stabilization while minimizing the duration and amount of low-temperature hot water production, thereby reducing energy loss.
Solution Approach 2:
The heat accumulating operation is divided into periodic stages: an initial period with lower compressor frequency for temperature stabilization, followed by a main heating period with higher frequency for efficient operation. This periodic structure balances system stability requirements with energy efficiency goals.
3Speed
If the compressor frequency is increased linearly as in conventional systems, then the system responds quickly to heating demands, but the amount of medium-temperature water accumulates reducing overall efficiency
Solution Approach 1:
Instead of linear frequency increase, the system uses a two-stage dynamic frequency adjustment: maintaining a lower frequency during the temperature stabilization period, then transitioning to a higher frequency. This dynamic control prevents the accumulation of medium-temperature water that would occur with linear frequency increase, thereby improving energy efficiency while maintaining adequate response speed.
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 the amount of medium-temperature water in the tank, delaying its increase and minimizing the decrease in energy consumption efficiency, especially at the end of the heat accumulating operation, by controlling compressor frequency and water flow rates.
Implementation Method 1
a compressor (3) for compressing refrigerant
Implementation Method 2
heat exchange means for heating the heating medium using heat of the refrigerant compressed by the compressor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A heat storage system includes a compressor that compresses refrigerant; a heat storage tank that stores a heating medium; heat exchange means provided outside the heat storage tank for heating the heating medium using heat of the refrigerant compressed by the compressor; a heat accumulating circuit including a feed path that feeds the heating medium flowing out of the heat storage tank to the heat exchange means, a return path that returns the heating medium heated by the heat exchange means into the heat storage tank, and a pump that circulates the heating medium; and control means capable of executing an initial operation that controls an operating frequency of the compressor at the beginning of a heat accumulating operation in which the heating medium heated by the heat exchange means is accumulated in the heat storage tank. The initial operation includes a first operation that maintains the operating frequency at a first frequency and, after the first operation, a second operation that maintains the operating frequency at a second frequency higher than the first frequency.