cooling with ground source heat pumps lessons learned from...
TRANSCRIPT
Cooling with ground source heat pumps – lessons learned from South-Eastern Asian countries
Kasumi Yasukawa1, Isao Takashima2,
Youhei Uchida1 and Gaurav Shrestha1
1 AIST
2 Akita University
Index
Introduction:
✓Why GSHP cooling in South-eastern Asia?
✓concerns in application of GSHP in South-
eastern Asia
Temperature survey
Demonstration projects
Summary
Why GSHP cooling in South-eastern Asia?
Increasing population, expanding industry
Urban heat island phenomenon
➢ Endless increase of electricity demand especially for cooling.
➢ Saving energy for cooling is essential in this region!
Concerns in application of GSHP in
South-eastern Asia
1. Is GSHP applicable in tropical region?
(temperature condition)
2. Is heat exchange rate sufficient? (for closed loop
systems)
3. Is drilling without cementing technically possible
by a local driller?
Introduction
GSHP is used worldwide, but is it applicable everywhere?
Cold
Moderate
Tropics
1. Is GSHP applicable in tropical region?
Monthly average atmospheric and subsurface temperature
Not really in tropics… They need cooling system, but underground is warm.
But it may be applicable in
tropical region if;
• Subsurface temperature is
rather low in the region
and/or
• Cooling demand of the
building is mainly in
daytime.
Introduction
Heat flow
coldheated
Subsurface temperature affected by groundwater flow
At recharge zones (high elevation), subsurface
temperature is lower than at discharge zones.
Underground can be used as cold source at
recharge zone, and may also be in the mid-plain.
Subsurface temperature profile with groundwater
flow in different zones of a plain/basin
1. Is GSHP applicable in tropical region?Introduction
2. Is heat exchange rate sufficient?
(in the heat exchange borehole)
Geology of the most basins and plains in South-eastern
Asia are unconsolidated sediments.
Since unconsolidated sediments have lower heat
conductivity than hard rocks, heat exchange rate in a
borehole must be low.
Therefore longer total drilling length is necessary in this
region. Higher drilling cost -> low cost performance
Is it real?
Introduction
Heat exchange affected by groundwater flow
In monsoon Asia, groundwater level in basins and plains are generally
high, and a saturated sediment has a high “effective heat conductivity”.
In addition, advection effect of groundwater flow may give even higher
“apparent heat conductivity”.
2. Is heat exchange rate sufficient?
Heat Conductivity (HC) of Rocks
A) “heat conductivity”: HC of dry rock
B) “effective HC”: HC of saturated rock
C) “apparent HC”: HC measured at field
with advection effect of groundwater
flow => actual heat exchange rate
➢ In water saturated zones, A<B<C
Introduction
So, even higher heat exchange rate than hard rock may be achieved!
Heat exchange with advection effect of groundwater flow
3. Is drilling without cementing technically
possible by a local driller?
To take advantage of advection effect of groundwater flow, a bare
borehole is needed as the borehole heat exchanger: no cementing,
no casing, and no bentonite mud circulation (formation of mud
cake blocks the groundwater flow).
But in South-eastern Asia, where unconsolidated sediments is
dominant in plains and basins, drillings have been done with
bentonite circulation, cementing and casing to avoid collapse of the
borehole.
Drilling with polymer is a solution.
Can it be done by local drillers?
Introduction
Introduction: Concerns in application
of GSHP in South-eastern Asia
1. Is GSHP applicable in tropical region?
2. Is heat exchange rate sufficient? (for closed loop system)
3. Is drilling without cementing technically possible by a local drilling company?
The answers to these three concern are shown in the following sections.
Introduction
Index
Introduction:
✓Why GSHP cooling in South-eastern Asia?
✓concerns in application of GSHP in South-
eastern Asia
Temperature survey
Demonstration projects
Summary
Subsurface TemperatureProfiles in Thailand
Bangkok
Ayuthaya
Nakhon Sawan
PitsanulokSukhothai
Kanchanaburi
Temperature
survey
Recharge zone
Recharge zone
Discharge zone
Intermediate zone
Discharge zone
Bangkok
Ayuthaya
Nakhon Sawan
Sukhothai
Kanchanabu
ri
Pitsanulok
subsurface (depth:0-50m)
--- annual mean
Temperature
surveySubsurface vs. atmospheric temperature in Thailand Monthly Ave.
Minimum
Monthly Ave.
Maximum
Subsurface
Ref: Yasukawa et al., 2009
Subsurface temperature around Hanoi, Vietnam
Subsurface temperature profiles measured in observation wells in Hanoi region
Temperature
survey
Ref: Yasukawa et al., 2009
• In Hanoi region, GSHP system
may show higher performance
for space cooling than in
Bangkok due to bigger difference
between atmospheric and
subsurface temperature.
• Winter in Hanoi is cool and humid.
GSHP heating may also be used
in the winter for heating/drying.
Temperature
survey
✓Is GSHP applicable in tropical region?: Yes, at least based on temperature survey results.
Even in Bangkok, a discharge zone, subsurface temperature is lower in daytime in hot season.
✓But is it really applicable? OK, let’s do demonstration experiments!
Subsurface temperature vs. atmospheric temperature in Hanoi region
GSHP Demonstration Projects in S-E AsiaPlace Period Subsurface Heat
ExchangerSurfaceSystem
Note
1. Kamphaengphet(DGR), Thailand
2006.10 –2008.3
57 m deep boreholewith double U-tube
Water-water chiller, fan coil
First experiment in tropic.Mostly made in Japan.
2. Ciang Mai (DGR), Thailand
2008.3 -2010.7
80 m deep boreholewith single U-tube +60 m horizontal tube
Same as above Moving the above system to another site.
3. Bangkok (KasetsartUniv.), Thailand
2010.7 -2012 ?
200 m horizontal tube Same as above Moving the above system to another site.
4. Bandung (ITB), Indonesia
2013.7 -2015?
200 m horizontal tube Remodel fromair-cond.
Cooling efficiency 25 % up (first comparable data).
5. Bangkok (Chulalong-korn Univ.), Thailand
2014.5 – 50 m deep boreholewith single U-tube x 3 (150 m)
Combined chiller& fan unit
Confirmation of highperformance.
6. Bandung (Western Java Energy Mineral Institute), Indonesia
2015.3 –2016?
100 m deep borehole with single U-tube
Remodel fromair-cond.
Heat exchanger made in Indonesia.
7. Sarabri (Chulalong-korn Univ.), Thailand
2015.6-2016.11-
300 m horizontal tube300 m horizontal tube
Combined chiller& fan unit
Machine made in ThailandRemodel from air-cond.
8. Pathumthani(Geology Museum, DMR) Thailand
2015.3 50 m deep borehole with double U-tube x 2 (400 m)
Combined chiller& fan unit
Mostly made in Japan.No cementing borehole for higher heat exchange.
9. Hanoi (VIGMR), Vietnam
2016.10- 50 m deep borehole with double U-tube x 2 (400 m)
Combined chiller& fan unit
Mostly made in Japan.No cementing borehole for higher heat exchange.
Blue: AIST and Akita Univ., Black: Akita Univ. … and local institute or university
Demonstration
Projects
Case 1: First GSHP experiment in tropical Asia with borehole heat exchanger in
Kamphaengphet.A GSHP system was installed at DGR office for room air-conditioner.
System performance and subsurface heat exchange capacity were monitored
over a year.
Demonstration
Projects
Experiment (Oct. 2006 -)
The room to be cooled
• Borehole was completed with normal
cementing and casing.
• Temperature change in the borehole and the
surroundings were monitored.
• All materials except for surface piping were
imported from Japan.
Heat pump
Borehole
Heat
Exchanger
Heat exchanger
(double U-tube)
Demonstration
Projects
Result of experiment in Kamphaengphet
System COP of 3 was achieved during stable operation period.
COP = provided heat / electricity consumption= (Toutlet – Tinlet)×Q2 / We
COP
HP operation temperature
Cooled room temperature
Outside temperature
Original room temperature
Demonstration
Projects
Result of experiment in Kamphaengphet
Result
Cooling system worked well and at a stable operation period
after adjustment of controlling temperature settings of the heat
pump, system COP of 3 was achieved.
Lessons learned:
To be economically feasible, careful setting and adjustment of
the HP parameters are necessary for higher performance.
In this experiment, the temperature of circulation fluid has risen
which reduces COP. For higher COP, a) a longer heat exchanger
and b) a borehole without casing/cementing is needed.
For cost reduction, use of local material is needed.
Demonstration
Projects
Experiment at Chulalongkorn University (from May 2014)
Second Presidential Office
(Right Hand Side is for Drilling)
Second Floor for Experiment
(Room Size: 2.8mX4.7m)
Case 5: Efficiency comparison with old system at Chulalongkorn University, Bangkok.
Demonstration
Projects
Drilling and Pipe Setting (Feb. 2014)
Drilling for 50m
Mud Flow by Drilling Cuttings Check for Geology
PE Pipe Setting to 50m Depth (100m length)
Just after 2 Drillings/Pipings
Recover Now (July 2014)
U-tube: only the end part is from Japan
Demonstration
Projects
Well 1
(10m+15m)
Well 2
(50m)
GHP
Outer
Unit
System Outline
Room for Cooling
GHP
Inner
Unit
Old AC
Data Logger
HP by Colona Co.
Demonstration
Projects
26
27
28
29
30
31
4 8 14 196 7 20 26 27 28August 2014
25
Cooling Operation of GHP and Old Air Conditioner
200W/h
800W/h
600W/h
400W/h
Atmospheric Temperature Room Temperature (Start 10am Stop 4pm, 6hrs)
Temp. (oC)
• 6 hour operation per day
• comparison not at the same time
Air Conditioner
GHP
by Sasimook Chokchai,
Chulalongkorn Univ.
Demonstration
Projects
GSHP cools the room more efficiently
than the old air conditioner
(1) Ratio of Average Power Consumption:
(213+293+423+357+203)/(615+667+702+695+573)=0.458* (Save 54%)
(2) Underground Heat Exchange Rate : 1.42oCx25 L/min.=35500cal/min.=2473W
(2473/150m=16.5W/m)
(3) COP: 2473Wx0.7?(Heat Exchange Efficency)/297.8W=5.8
* Correct old AC efficiency: 1489/(3252x0.68)=0.673 (Save 33%)
Cooling Operation of GHP and Old Air Conditioner Aug. 2014, 10:00-16:00 (6 hours)/day
Yellow Italic is Data of Old Air Conditioner by Sasimook Chokchai,
Chulalongkorn Univ.
Demonstration
Projects
33% higher efficiency than new air conditioner was confirmed!
Case 7: GSHP with Horizontal Heat Exchanger in Churalongkorn Univ., Saraburi.
Objective is cost reduction for drilling
Upper left:
Heat exchanger
of carpet styleUpper right:
Heat exchanger
of coil style
Lower left:
Ground source
heat pump
Lower right:
Fun coil unit in
office
June, 2015
Demonstration
Projects
Results of the experiment in Chulalongkorn University, Bangkok and Saraburi
Comparison of the performance with a new air-con was done in
Bankok as the first time.
Local material for heat exchange pipes are used in both Bangkok
and Saraburi. The pipe connection caused small leakages.
Horizontal system in Saraburi shows OK performance (may not be
as good as vertical system, but good cost performance).
Lessons learned
GSHP system in Bangkok showed 33% higher efficiency than a
new air-con.
For installation cost reduction, effective combination of
horizontal and vertical system is recommended.
DGRの掘削機(利根ボーリンク製)
泥水の比重計測
錘とUチューブを接続
Installation of pipe
GSHP unit
Heat Exchangers (50m deep)
Demonstration
Projects
Fun coil unit of GSHP system
室内機
Souvenir shop at 2nd Floor
ResultImprovement achieved
➢ Heat exchanger pipes were connected by Electric Fusion System to avoid
leakage.
➢ Thai crews drilled two heat exchangers with 50m depth: no cementing, no
casing for higher heat exchange rate.
Necessary improvement
➢ Drilling with mud circulation was conducted: it took one week to be
completed, including the time for washing away the mud cake (bentonite).
Demonstration
Projects
Master plan of system arrangementFCU : Fun Coil Unit
HP : Ground Source Heat Pump
HX : Borehole type heat exchanger (50m depth)
Case 9: VIGMR, Hanoi, Vietnam(October, 2016)
Vietnam Institute of Geoscience and Mineral Resources (VIGMR)
Demonstration
Projects
Results➢ VIGMR completed drilling of two heat exchangers (50m deep) in three
days, with Synthetic Polymer as drilling mud, which it easy to use.
(Same system arrangement as the one in Geological Museum in Thailand.)
Lesson Learned:
✓ Drilling borehole without bentonite, cementing or casing can be done by
local driller efficiently, by using polymer as mud fluid.
Drilling machine (no casing, no cementing for higher heat exchange rate)
Demonstration
Projects
Preparation of heat exchange pipeInstallation of pipe from 2nd floor
GSHP unit Fun coil unit in DG’s room
Demonstration
Projects
In Hanoi, heating system is not common. It’s nicely warm in cold season!
Summary
Acknowledgement➢ These collaboration researches have been done under CCOP Groundwater Sub-
Project “Development of Renewable Energy for GSHP System in CCOP Regions.”
• Experimental operation of GSHP systems for cooling only has beenconducted in Thailand, Indonesia and Vietnam.
• To be economically feasible, careful setting and adjustment of thesystem parameters are necessary to get higher performance withhigher electricity savings.
• High performance has been confirmed at a test site in Bangkok.
• System with local manufacturing would be a key for cost reduction.
• Cost performance may be optimized by selection of horizontal orvertical heat exchangers depending on local subsurface condition.
• Drilling technology (no cementing, no casing, no bentonite) wouldbe a key for higher heat exchange rate by vertical borehole.