Heat Pump performance boost with the use of solar collectors

Professor Tariq Muneer, Edinburgh Napier University
Aymeric Girard a* , Lorraine McCauley b

a* Faculty of Engineering and Sciences, University Adolfo Ibanez, Av. Padre Hurtado 750, Altos del Sporting. Viña del Mar, Chile

b School of Engineering and Built Environment, Edinburgh Napier University,10 Colinton Rd. Edinburgh, EH10 5DT, UK

The need for an energy performance improvement in Ground-Source Heat Pumps (GSHP) for the residential and commercial sectors has historically been identified as a result of regular project work undertaken by European Energy Centre. It is clear that there is a dearth of in-situ measured data that is available on COP of GSHP and their equivalent performance. In order to achieve higher heat pump COP through the use of roof-top thermal solar collectors, the Edinburgh Napier University team has been commissioned to undertake research and investigate the performance of such systems. Heretofore such systems shall be called as ‘Solar-assisted Ground-Source Heat Pumps (SGSHP)’. Figure 1 provides an illustration of a SGSHP system.

This article presents an investigation on the use of solar collectors to improve the performance of Heat Pumps (HP). The work has been developed following four main development areas; a review of the on-site solar and ground energy resource, an analysis on the influence of the solar collector in achieving better performance, a development of a simulation tool for the performance of the solar-assisted ground source heat pump and conclusions.

This study shows that the use of solar collector in northern latitude country has little impact on the heat pump performance improvement in winter. However, the system works slightly better in spring/autumn. The system is more suitable for cold countries with high irradiance. Table 1 presents a summary of the findings.

 

Figure 1 Schematic of a Solar-assisted Ground Source Heat Pump (SGSHP)

Table 1: Comparison between the 3 sources of heating

 

GSHP (0m² of solar)

SGSHP (63m² of solar)

Conventional gas boiler

W compressor, kWh

1760

1662

-

W pumps, kWh

28

37.5

-

Energy space heating, kWh

8,632

8,632

8,632

Average yearly COP (efficiency for gas boiler)

4.9

5.2

0.9

Total electricity, kWh

1,788

1,699.5

-

Total gas used, kWh

-

-

9,495

Cost of energy, £/year

217

206

345.62

Overall cost, £/year Fuel usage + fuel standing charge + maintenance cost + equipment replacement cost

1,517

In view of the quoted solar collector prices this option is uneconomical on a monetary basis.

1,055

CO2 emission, kg

971

923

1747


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