Heat Pump Chiller Circuit Switching for Pump Head and Flow Balance
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Solution Overview
Problem
Heat pump systems face inefficiencies due to insufficient pump head at high flow rates and reduced efficiency at low flow rates, leading to increased costs and reduced performance in systems with multiple heat pump chillers connected in series or parallel configurations.
Innovation Solution
A heat pump system with switchable parallel and series circuits allows heat pump chillers to adjust their connection based on flow rates, using solenoid valves to ensure optimal water flow and reduce the need for high-capacity pumps, thereby maintaining high efficiency and COPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If heat pump chillers are connected in series to a cold/hot water circuit, then the pipe length is long, but the water pump head becomes insufficient at high flow rates
Solution Approach 1:
The system dynamically switches between series and parallel circuit configurations based on operating conditions. When water flow rate increases and pump head becomes insufficient, the system switches from series to parallel connection, reducing the effective pipe length and allowing water to flow out completely without requiring an oversized pump.
2Stress or pressure
If heat pump chillers are connected in parallel to a cold/hot water circuit, then the pump head is sufficient, but the water flow rate to individual chillers decreases
Solution Approach 1:
The system adapts its circuit configuration dynamically. When water flow rate is low and pump head is excessive, the system switches from parallel to series connection, increasing the water flow rate to individual chillers and maintaining high heat transfer coefficients, thereby preventing efficiency reduction.
3Stress or pressure
If a pump with higher head or larger capacity is used to ensure sufficient pump head, then the pump head is adequate, but the motive power and running costs increase
Solution Approach 1:
Instead of using a fixed oversized pump, the system changes the circuit configuration parameter (series/parallel switching) to adapt to different operating conditions. This allows a standard-capacity pump to provide sufficient head when needed while consuming less power during normal operation, eliminating the need for oversized equipment and reducing running costs.
4Stress or pressure
If water flow rate to individual chillers is reduced in parallel connection, then the pump head is sufficient, but the heat transfer coefficients decrease and efficiency is reduced
Solution Approach 1:
The system dynamically adjusts its configuration to maintain optimal water flow rates to individual chillers. When operating in series mode, each chiler receives adequate water flow to maintain high heat transfer coefficients and efficiency, while the pump head remains sufficient due to the longer pipe length being compensated by the series arrangement.
Data Source
AI summary
An object is to provide a heat pump system that can eliminate an insufficient pump head when the flow rate is high, a decrease in efficiency when the flow rate is low, and so on, so that the heat pump system can be operated constantly at high efficiency. In a heat pump system (1) in which a plurality of heat pump chillers (4A to 4D) are connected to a single cold/hot water circuit (2) equipped with a water pump (3), the plurality of heat pump chillers (4A to 4D) are divided into a plurality of series, the heat pump system including a parallel circuit (5) that connects the heat pump chillers (4A to 4D) of the individual series in parallel to the single cold/hot water circuit (2) and a series circuit (6) that connects the heat pump chillers (4A to 4D) of the individual series in series to the single cold/hot water circuit (2), wherein the parallel circuit (5) and the series circuit (6) are switchable to each other via a switching means (7, 8, and 9).