Direct Exchange Geothermal Cooling With Compact Ground Loops

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional geothermal direct exchange heating/cooling systems face installation limitations due to large land area requirements for sub-surface heat exchange tubing, which precludes their application in commercial and high-density residential settings, and suffer from inefficiencies in oil separation and refrigerant management, leading to maintenance issues and increased operational costs.

Innovation Solution

The design improvements include a compressor sizing reduction to 80-95% of conventional capacity, an advanced oil separator with 0.3 micron filtration efficiency and metered oil return, use of R-410A refrigerant with higher operational pressures, and optimized component sizing and configurations such as receiver sizing and expansion devices to enhance efficiency and reduce maintenance needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional geothermal DX systems use large sub-surface heat exchange tubing areas, then heat exchange efficiency is improved, but land area requirements increase making the system inapplicable to commercial and high-density residential settings

Engineering Contradiction:

Improveheat exchange efficiencyVSAvoidland area requirement

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The patent changes the physical parameters of the heat exchange system by using smaller diameter copper tubing (3/8 inch or less) with higher heat transfer coefficients, and increasing the refrigerant flow velocity and temperature differential. These parameter changes allow achieving the same heat exchange capacity with significantly reduced tubing area, making the system suitable for commercial and high-density residential applications where land area is limited.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If compressor size is reduced to 80-95% of conventional capacity, then energy consumption is lowered, but system cooling/heating capacity may be insufficient

Engineering Contradiction:

Improvecompressor energy consumptionVSAvoidsystem capacity

Core Design Contradiction:

Use of energy by moving objectVSPower

Solution Approach 1:

The patent changes the operating parameters of the refrigeration cycle by optimizing the refrigerant charge amount, adjusting the expansion valve opening degree, and modifying the condenser and evaporator surface areas. These parameter adjustments allow the reduced-compressor system to maintain adequate cooling capacity while operating at lower energy consumption levels through improved cycle efficiency.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent designs the compressed refrigerant vapor to serve multiple functions: it provides the primary cooling effect in the evaporator, and simultaneously acts as a heat source for the condenser where it condenses. This multi-functional use of the compressed refrigerant allows the system to maintain capacity with a smaller compressor by maximizing the utilization of refrigerant heat transfer potential.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If advanced oil separation with 0.3 micron filtration is implemented, then oil management efficiency is improved, but device complexity and initial cost increase

Engineering Contradiction:

Improveoil separation efficiencyVSAvoidoil separator complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical oil separation systems with a simplified approach using a centrifugal oil separator that utilizes centrifugal force generated by refrigerant flow. The 0.3 micron filtration is integrated as a simple screen or mesh element rather than a complex filtration system. This mechanical substitution reduces device complexity while maintaining high oil separation efficiency through the combined effects of centrifugal separation and fine mesh filtration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

These improvements result in increased operational efficiencies, reduced maintenance requirements, and lower installation costs by minimizing land area usage, improving oil management, and optimizing refrigerant flow, thereby lowering energy consumption and extending system lifespan.

Implementation Method 1

an oil separator with an ability to filter to 0.3 microns and is preferably in excess of 98% efficient

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Implementation Method 2

transfer geothermal heat to or from the sub-surface elements

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

circulate a refrigerant fluid... in sub-surface refrigerant lines... to transfer geothermal heat

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8931295B2Multi-faceted designs for a direct exchange geothermal heating/cooling system

Publication Date: 2015.01.13 WIGGS B RYLAND

AI summary

A direct exchange heating/cooling system with at least one of a reduced compressor size, with a 500 psi high pressure cut-off switch, with a 98% efficient oil separator, with extra oil, operating at a higher pressure than an R-22 system, with receiver design parameters for efficiency and fox capacity, with geothermal heat exchange line set design parameters, with special heating/cooling expansion device sizing and design, with a specially sized air handler, and with a vapor line pre-heater.