Application of a variable-speed ground-coupled liquid desiccant air-conditioner to multi-story office buildings in temperate regions

ABSTRACT

A new variable-speed ground-coupled liquid desiccant air-conditioner was proposed and applied to a multi-storey office building in a temperate city of Kunming in China. Dynamic system simulations were performed to compare its performance with a constant-speed ground-source heat pump system. It was found that the use of the new system for a single-floor office reduced the annual unbalanced load to the ground heat exchanger borefield by nearly 70% together with a borehole depth reduction of up to 30%. For the case of a multi-storey office building, the number of floors served could be increased by 144% together with a reduction of CO₂ emission by 43%. The results highlighted the merit of the new hybrid system with enhanced applicability when it was applied to a multi-storey office building in a temperate city.

KEYWORDS:

• Ground-source heat pump
• Ground heat exchanger borefield
• Liquid desiccant dehumidifier
• Variable-speed control
• Dynamic simulation

Nomenclature

COP	=	coefficient of performance
T	=	temperature (°C)
x, y	=	ground measurement in the transverse direction (m)
z	=	measurement in the vertical direction (m)

Subscripts

bf	=	borefield fluid
i, j, m	=	ground discretization step designations in the z-, x- and y-directions
g	=	ground
max	=	maximum
out	=	outlet

Abbreviations

ASHP	=	air-source heat pump
GHE	=	ground heat exchanger borefield
GCLDAC	=	ground-coupled liquid desiccant air-conditioner
GSHP	=	ground-source heat pump
VSGCLDAC	=	variable-speed ground-coupled liquid desiccant air-conditioner
VSGSHP	=	variable-speed ground-source heat pump

Additional information

Funding

The authors would like to gratefully acknowledge the funding support provided to this research work by the Research Grants Council of Hong Kong under the General Research Fund for Project No. 713710.