Performance Analysis of Air Cooled Heat Pump Coupled with Horizontal Air Ground Heat Exchanger in the Mediterranean Climate

Cristina Baglivo,Paolo Congedo,Sara Bonuso

doi:10.3390/en11102704

Abstract

A concept of Air-Cooled Heat Pump (ACHP) coupled with a Horizontal Air-Ground Heat Exchanger (HAGHE), also called Horizontal Earth-To-Air Heat Exchanger (EAHX), has been proposed. The Air-Cooled Heat Pump is a system which transfers heat from outside source (air) to inside sink (water) and vice versa in summertime. The innovation is to provide a geothermal treatment of pre-heating/cooling of air before meeting the evaporator in winter or the condenser in summer of the heat pump. Besides, it is known that the variations of the ground temperature, respect to the external air one, are mitigated already in the first layers of the ground throughout the year, due to the high thermal inertia of the ground, letting the heat pump work with more mitigated conditions, improving the performances. The behaviour of HAGHE has been investigated by varying the length and the installation depth of the probes, the air flow rate and the ground thermal properties. All the combinations have been implemented using TRNSYS 17 software (Transient System Simulation Program) to obtain the outlet temperatures from HAGHE, resulting from the 54 configurations. The results are compared in terms of Coefficient of Performance (COP) in wintertime and Energy Efficiency Ratio (EER) in summertime between configurations with and without the coupling with HAGHE. In addition, two seasonal performance SCOP and SEER coefficients have been calculated considering, not only the inlet air temperatures into the Air-Cooled Heat Pump, but also their frequency of occurrence, the off-set external temperature (16 °C), the nominal external temperature and heating and cooling loads.

Highlights

The energy efficiency of building sector is one of the most key issues about the energy policies of the European Union, since the construction sector constitutes 40% of the global energy consumptions in the developed territories
This study aims to demonstrate how it is possible to increase the performances of an air-cooled heat pump with the use of Horizontal Air-Ground Heat Exchangers (HAGHE)
The Air-Cooled Heat Pump (ACHP)-HAGHE system has been investigated by varying parameters such as the length and the installation depth of the probe, the air flow rate and the ground thermal properties in terms of Coefficient of Performance (COP), Efficiency Ratio (EER) and Seasonal Index as Seasonal Coefficient of Performance (SCOP) and Seasonal Energy Efficiency Ratio index (SEER)

Summary

Introduction

The energy efficiency of building sector is one of the most key issues about the energy policies of the European Union, since the construction sector constitutes 40% of the global energy consumptions in the developed territories. The European Commission has fixed the goals to encourage an intelligent, sustainable and inclusive growth with the climate and energy package called “20-20-20”. In the climate and energy sectors the aims of the EU 20-20-20 become an important status considering the necessity to cut the gas emissions of 20%, as well as to cover the 20% of the final energy consumptions with renewable energy sources, and to improve the energy efficiency of 20%. UE puts in evidence the significance of reaching smart growth with simultaneous reduction of energy consumptions and investment and maintenance costs, through the strengthening of energy efficiency measures and the adoption of many policies in this regard.

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