Heat Pump Pressure Spike Eliminator for Stable Pool Heating

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Solution Overview

Problem

Heat pump type pool heaters experience high hydraulic pressure spikes upon start-up after extended idle periods, leading to compressor shutdown due to insufficient gaseous refrigerant to absorb the pressure increase, which is not effectively addressed by standard solutions and results in reduced water heating capacity.

Innovation Solution

A pressure spike eliminator apparatus is integrated into the heat pump circuit, featuring a tubular body with a sealed section of refrigerant tubing that acts as a 'shock absorber' to prevent overpressurization by allowing a gas pocket to form, reducing the risk of compressor shutdown and refrigerant migration during downtime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If refrigerant charge is reduced to eliminate pressure spikes, then compressor shutdown is prevented, but water heating capacity is lowered

Engineering Contradiction:

Improvecompressor operation continuityVSAvoidwater heating capacity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The refrigerant system is segmented into two distinct volume zones: a large receiver tank and the water-to-refrigerant heat exchanger. The receiver serves as a separate reservoir that isolates the heat exchanger from excessive refrigerant migration, preventing pressure spikes while maintaining adequate refrigerant charge for heating capacity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A receiver tank is introduced as an intermediary component between the compressor and the water-to-refrigerant heat exchanger. This receiver acts as a buffer zone that absorbs excess refrigerant during idle periods, preventing it from migrating into and filling the heat exchanger, thereby eliminating pressure spikes without reducing the overall refrigerant charge.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If standard receivers are used to address pressure spikes, then some mitigation is achieved, but costly refrigerant addition is required and effectiveness is limited

Engineering Contradiction:

Improvepressure spike mitigationVSAvoidrefrigerant charge

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The receiver is designed with specific volume parameters optimized for the application - a volume of at least 0.5 gallons (preferably 1.0 gallon or more) that provides sufficient buffer capacity to absorb refrigerant migration without requiring additional refrigerant charge. This parameter optimization achieves effective pressure spike mitigation while maintaining the original refrigerant charge levels.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If refrigerant migrates to the water-to-refrigerant heat exchanger during idle periods, then the heat exchanger fills up, but this causes pressure spikes upon compressor start-up

Engineering Contradiction:

Improverefrigerant distributionVSAvoidhydraulic pressure spike

Core Design Contradiction:

Quantity of substanceVSStress or pressure

Solution Approach 1:

The receiver tank is positioned upstream in the refrigerant circuit to provide beforehand cushioning against pressure spikes. During idle periods, the receiver absorbs migrating refrigerant vapor, creating a cushion that prevents the heat exchanger from filling up. When the compressor starts, this pre-established cushion prevents sudden pressure increases by providing a buffer zone for pressure equalization.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

The solution effectively eliminates compressor start-up pressure spikes, preventing unnecessary shutdowns and maintaining the heat pump's water heating capacity without the need for costly refrigerant additions.

Implementation Method 1

there is not enough gaseous refrigerant between the compressor and expansion device to absorb the sudden increase in pressure produced by the scroll compressor on unit start-up

Methodology Applied

Scientific EffectGas compressibility:

Implementation Method 2

too much refrigerant migrating to the relatively small volume water-to-refrigerant heat exchanger used on heat pump pool heaters that fills up the space inside the heat exchanger during the off cycle over an extended time

Methodology Applied

Scientific EffectRefrigerant migration:

Data Source

PatentUS9046286B2Heat pump pool heater start-up pressure spike eliminator

Publication Date: 2015.06.02 RHEEM MFG CO

AI summary

In a heat pump pool heater, undesirable compressor-created pressure spikes resulting from start-up of the heater after extended idle periods thereof are substantially eliminated by the incorporation in the heat pump refrigerant circuit of a specially designed pressure spike eliminator structure. The spike eliminator structure includes an enclosed hollow wall structure extending around a first refrigerant tubing portion disposed between the heat pump circuit compressor and condenser and forming a cavity around the first refrigerant tubing portion, and a transfer tube directly connected to a second refrigerant tubing portion disposed between the condenser and expansion valve and intercommunicating the interiors of the cavity and the second refrigerant tubing portion.