Thermal Storage Coupled to a Ground Source Heat Pump in

a Public Services BuildingCOIMBRA

Andre Quintino Duarte

Oradea, 06 June 2012

Demonstration Building

Total area: 3250m2

Four floors

Two public services installed

Offices, laboratories, conference room

Capacity for 250 permanent workers + 72 temporary people in a conference room

Located close to a river

“Fábrica dos Mirandas”

Demonstration Building

Demonstration Building

• The heated /cooled spaces are located in level 3 of the building (last floor).

• 22 rooms (offices)• Approximately space conditioned area 600 m2

22 Rooms

Thermal Solution• Before 2012: Air Conditioning

– Low Efficiency;– Noisy;– Outdated technology;– COP between 2 and 3.

• February 2012: Ground Source Heat Pump (GSHP)– High Efficiency;– Very Silent;– New technology;– COP between 5 and 6.

• November 2012: GSHP + Thermal Storage– Increase Efficiency;– Avoid Expensive Electricity Periods;– Reduce Building Footprint.

Thermal Storage• The thermal storage tank is to be located in a room

adjacent to the machinery room. It is planned to have a volume of 3.5m3 (40% water + 60% PCM).

• Research is being conducted with the support of the Fluids Thermal Transfer Group of the Department of Mechanical Engineering on the best design of the tank to ensure optimal heat transfer and to ensure that the storage maximum capacity of the PCM modules is used.

• It was found that the most suitable material would be the S46 salt hydrate from PCM products Ltd (UK)

Thermal Storage Tank

Tank Dimensions:1,5m; 0,8m; 3m (H; W; L)

With a Thermal Capacity of 100 KWh.

(Currently under construction)

To be installed late this year in November.

Thermal Needs on a Typical Monday

100 kWh Thermal Storage for 2 hours.

Thermal Needs on a Typical Friday

100 kWh Thermal Storage for 3,5 hours.

Electricity Price in Portugal

Period Period Electricity Prices Peak Power Prices

Peak Period9 AM to 10:30 AM6 PM to 8:39 PM

0,2078 €/kWh 0,4025 €/kW

Middle Peak Period8 AM to 9 AM

10:30 AM to 6 PM 0,1112 €/kWh -

Off Peak Period10 PM to 2 AM6 AM to 8 AM

0,0732 €/kWh -

Special Off Peak Period

2 AM to 6 AM 0,0680 €/kWh -

0:00

0:45

1:30

2:15

3:00

3:45

4:30

5:15

6:00

6:45

7:30

8:15

9:00

9:45

10:3

011

:1512

:0012

:4513

:3014

:1515

:0015

:4516

:3017

:1518

:0018

:4519

:3020

:1521

:0021

:4522

:3023

:15

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Typical Electrical Consumption

Hours

Ele

ctri

cal

Po

wer

(kW

)

Control System

Control Hardware

Piping System

Heat Pump• Reversibility is done on the

water side in order to always be in counter current on the heat exchangers.

• This is achieved by 3-way motorized valves

CondEvap

Simplified Schematics of the Hydraulic Installation

75 mm Diameter PPR Pipes in the main sections

Thermal Storage

Control Software

Preliminary Test Results

Without Thermal Storage: COP = 6,03

With Thermal Storage: (In November)

Thank you