Upload
idigiti
View
214
Download
0
Embed Size (px)
Citation preview
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 1/15
INTERNATIONAL JOURNAL OF ENERGY RESEARCHInt. J. Energy Res. 2006; 30:291–305Published online 15 August 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/er.1148
On the technical feasibility of gas turbine inlet air cooling
utilizing thermal energy storage
Y. H. Zurigat1, B. Dawoud2,n,y and J. Bortmany3
1Mechanical Engineering Department, The University of Jordan, Amman, Jordan2Chair of Technical Thermodynamics, RWTH-Aachen University, Schinkel Str. 8, D-52062 Aachen, Germany
3Petroleum Development Oman, P.O. Box 81, Postal Code 113, Oman
SUMMARY
The potential of using thermal energy storage (TES) in the form of ice or chilled water to cool gas turbine
inlet air is evaluated for a remote oil field location in the Sultanate of Oman using local hourly typicalmeteorological year weather data. It is found that under the conditions investigated seasonal TES in chilledwater storage tanks or ice bins for the location considered is prohibitively expensive and thus notrecommended. Application of partial TES option shows that the cool storage does not result in anynoticeable reduction in the chiller size. Hence, TES whether seasonal, partial, or full storage is not a viableoption for the considered location, especially in the absence of time-of-use utility rate structure. Copyright# 2005 John Wiley & Sons, Ltd.
KEY WORDS: gas turbine; inlet air cooling; thermal energy storage
1. INTRODUCTION
Ambient conditions influence the performance of gas turbine power plants. As the ambienttemperature is decreased the power output and the efficiency are increased. Hence, inlet air
cooling has been considered for boosting the power output of gas turbine during hot summer
months when the electric power demand is high due to air conditioning load. Depending on the
type of gas turbine, a reduction of about 0.2% in the heat rate and an augmentation of about 0.5
to 0.9% in electrical power production for every degree Celsius drop in the compressor’s inlet air
temperature are achieved (Chaker and Meher-Homji, 2002). Thermal energy storage (TES) is a
technique which may be integrated with gas turbine power generation plants to store chilled
water or ice during off-peak periods to be used for inlet air cooling during peak periods. A
comparison of the ice and chilled water storage systems is shown in Hasnain (1998).
Received 21 August 2004Revised 11 March 2005
Accepted 1 May 2005Copyright# 2005 John Wiley & Sons, Ltd.
yE-mail: [email protected]
Contract/grant sponsor: Petroleum Development of Oman (PDO); contract/grant number: 2002-52
nCorrespondence to: Dr Belal Dawoud, Chair of Technical Thermodynamics, RWTH-Aachen University, SchinkelStr. 8, D-52062 Aachen, Germany.
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 2/15
In their study of overall economics of the gas turbine power augmentation benefits Ondryas
et al . (1991) considered TES as an option for a power generation facility comprised of four GE
Frame 7E gas turbine generators. They investigated the use of chilled water and ice TES systems
for the peak hours of the peak months of the year. For chilled water TES they considered both
full and partial TES options. For an ice TES system of equivalent cooling capacity thecalculated storage tank volume 7–14 times less than the chilled water TES tank volume. Based
on their study they concluded that the size of chilled water TES may result in space constraints
and large costs.
Ice storage has been applied for gas turbine inlet air cooling at different locations
around the world. A system installed at a gas turbine power generation plant (ISO rating of
59.8 MW and a peak rating of 65.2 MW) at a Nebraska company used ice storage to cool the
inlet air from 38 to 48C (Stewart, 1998). A net power increase of approximately 12 MW (21%)
has been achieved (a power boost of 0.59% 8C1). To cool the gas turbine inlet air a study
conducted by Antoniak et al . (1992) examined both seasonal TES of cold water and diurnal TES
of ice. The former termed aquifer thermal energy storage (ATES) was designed to store cold
water during winter time in an aquifer. The water is chilled during winter by cold winter air in a
conventional cooling tower and injected into the aquifer through a number of supply wells. Thecool water is then withdrawn during summer months to supply the cooling load of gas turbine
inlet air cooling system. Economic assessment of the seasonal TES technique showed that under
the climatic conditions of Minneapolis area inlet air cooling with ATES provided lower cost
electricity than installing extra power generation capacity (or installing larger gas turbines) to
meet the same increase in power output. In contrast, diurnal TES of ice showed that inlet air
cooling with ice storage is 5–20% more expensive than installing larger gas turbines to meet the
power demand.
Somasundaram et al . (1993) addressed some of the TES systems that are readily
applicable to be combined with cogeneration systems. With regard to precooling the gas
turbine inlet air with cold water supplied by ATES system, their preliminary results indicated
that the preferred system will depend on site-specific conditions and operating requirements.
The cost effectiveness of the ATES system varies significantly with site-specific geologicconditions.
In his review of cool thermal storage Hasnain (1998) stated that a 1996 U.S. Department of
Energy study showed that a thermal energy storage for turbine inlet air cooling system can be
installed at a cost of 150–250 U.S.$ kW1 of incremental power boosting. In their analysis of
cool storage integrated with a typical commercial building air conditioning system,
Hasnain et al . (1999) concluded that cool storage is a cost-effective tool for both demand and
utility sides, i.e. building air conditioning and gas turbine inlet air cooling, respectively.
However, it must be noted that the cooling load profile used in their analysis perfectly suits
thermal storage, i.e. low night load and high daytime load. This is typical of commercial and
public buildings. The analysis of gas turbine inlet air cooling (Hasnain et al ., 1999) was not
based on detailed calculations of a specific gas turbine or actual local weather profiles. Their
conclusion of the cost effectiveness of cool storage for gas turbine inlet air cooling is basedmainly on the experience of similar systems in U.S.A. where a number of TES systems have been
operated. In fact, a thermal storage system using ice for gas turbine inlet air cooling was
designed to operate on a weekly cycle (Bakenhus, 2000). Table I gives detailed specifications of
the system which was then the largest of its kind in the world. Bakenhus (2000) reported that the
cost effectiveness of the system was based on the lowest first cost option for additional
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY292
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 3/15
Table I. Specifications of a gas turbine inlet air cooling system using ice storage(compiled from Bakenhus, 2000).
Gas turbineGas turbine model (simple cycle) GE MS7001BDesign temperature drop, 8C 37.7 to 4.9=32.8Corresponding power increase, MW From 53.1 to 67.1=14 MWPer cent increase per degree Celsius, % 8C1 0.82Corresponding heat rate improvement, % 6
Ice makerIce maker capacity, kW (ton) 1930 (550)Evaporator type 3 shell and tube evaporatorsCondenser type EvaporativeIce maker power supply Off-peak powerIce maker power consumption (compressor, condenser, pumps, etc.)
per ton of refrigeration, kW ton11.27
Compressor (screw type) motor power, kW (hp) 522 (700)Operation period 148 h week1
Ice storage tank (cylindrical )Volume, m3 (gallons) 4300 (1.15 million)Dimensions (heightdiameter), m 924Buried depth, m 6Construction material Cast-in-place concreteStorage capacity, kWh (ton-h) 131 240 (37 400)
Inlet air cooling systemOperation mode (4 h a day, 5 days a week) Weekly cycleGas turbine inlet heat exchanger
Type Coil bank (24 coils)Surface area, m2 125Inlet air volume flow rate, m3 s1 203.4Inlet air mass flow rate (at 398C and 34% rh), kg s1 250.0
Coil leaving air velocity, m s1
1.5Moisture condensation rate at the coils, ‘ s1 (gpm) 2.5 (40)
Circulating cooling waterEntering temperature, 8C 1.1Leaving temperature, 8C 7.7Flow rate, ‘ s1 612
Cooling water circulating pumps (two centrifugal horizontal split case)Power, kW (hp) 186 (250)Redundancy: one pump is sufficient for the inlet cooling system operating
on a design day at 7.28C inlet air temperature which only results in1 MW less than design power output improvement.
EconomicsGas turbine initial (installed) cost, $ kW1 300
Inlet air cooling system installed cost, $ kW1
165Avoided cost on new peaking generating capacity, $ kW1 100
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 293
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 4/15
generating capacity. That is, the TES system installation cost was $165 kW1 of capacity
compared with an initial cost of $300 kW1 of capacity from an additional gas turbine. Table II
gives the details of another project (Anderpont, 2001) for gas turbine inlet air cooling (GTIAC)
system coupled with chilled water TES for a combined cycle power plant with district heating
and cooling. Although he projected attractive project net present value Anderpont (2001) gaveno details on economic assessments.
Based on the literature review presented in the foregoing it is seen that the application of TES
to GTIAC is site specific. Furthermore, most of the studies use a single design day cooling load.
The objective of this study is to examine the technical feasibility of using TES for GTIAC based
on cooling load profiles calculated based on hourly typical meteorological year (TMY) weather
data. The question posed now is whether to use a chiller alone for gas turbine inlet air cooling or
to use a chiller in combination with TES. The analysis is applied to one remote oil field location
(Fahud) in the Sultanate of Oman.
Table II. Chilled water TES GTIAC for a combined cycle power plant (compiled from Andrepont, 2001).
Location Florida/U.S.A.Combined cycle GT power (nominal), MW 40 (32 from GT+8 from ST)Heat recovery steam generator, kg s1 11.34 (40 823 kgh1)Cooling source and capacity, MW (ton) Electric+absorption chillers 5.043 (17 750)
Inlet air cooling system design conditionsDesign inlet air T db/T wb Temperatures, 8C/8C 35/26Design outlet air temperature, 8C 10Chilled water supply temperature, 8C 4Chilled water return temperature, 8C 21 for GT inlet air cooling and 13 for district coolingAir flow rate, m3 s1 103.45Heat exchanger 4 banks of coilsAir side pressure drop, Pa (inch H2O) 30 (1.2)
Chilled water storageType StratifiedVolume, m3 19 000Dimensions (DH ), m 35.420.4Material Welded steelCapacity, MWh (ton-h) for 200.6 (57 000) for}Inlet air cooling, MW }2000}District cooling, MW }3500Discharge duration, h 10
PerformanceIncreased GT power (from 35 to 108C), MW 26 to 34=8Heat rate improvement, % 6
Economics unpublished except ‘the NPV for the project totalling several millions of dollars’ (Andrepont,2001)
RemarksThe chillers+TES are sufficient for cooling the inlet air+district cooling. Inlet air cooling eliminated theneed for two new chillers of combined capacity of 3325 ton.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY294
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 5/15
2. SYSTEM DESCRIPTION
A block diagram of a generic GTIAC system is depicted in Figure 1. The basic building blocks
are the chiller, its cooling tower, the air heat exchanger, and the interconnecting piping. The
exhaust gases of the gas turbine may be used directly to drive the sorption chiller. Some of the
available chillers are hot water or steam driven, while the others are direct fired. For this reason,
a steam boiler is incorporated as optional equipment. Cold fluid from the chiller is pumpedthrough the air heat exchanger, where the coolant is heated and returned to the chiller, while the
inlet air is cooled prior to entering the compressor. A TES system is incorporated to store the
cooling capacity required or the excess cooling generated.
The required cooling water for both the condenser and absorber of the absorption chiller is
provided using cooling tower. Alternatively, evaporative or air-cooled condensers and absorbers
might be used with some types of chillers. Including storage and its associated piping loop
increases the number of system components, but must allow the chiller and cooling tower
components to be downsized.
3. ANALYSIS
It is well known that when thermal loads fluctuate, the potential exists for storing thermal
energy (cooling or heating) to furnish the high load peaks. TES may be designed on seasonal or
diurnal bases. Seasonal cool storage is quite expensive as the volume of storage and thermal
losses are high. For example, assume a cooling load of 1 MW is to be furnished by thermal
storage such that it covers 25% of the summer months of May, June, July and August or 738 h
Figure 1. Generic inlet air cooling system.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 295
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 6/15
[0.25 24 (31+30+31+31)]. Ignoring losses this translates into 738 MWh of cooling energy
stored. About 3 kg of ice is required to store 1 MJ of cooling (Dincer and Rosen, 2002). Hence,
a 7970400kg (738 3600 3) or 7971 m3 of ice is required. For a 2 m deep storage tank the
area needed is 3986 m2. This area is calculated without accounting for thermal losses which for
such a large area are quite significant considering the long storage period.If chilled water is used instead of ice different storage devices exist, their purpose is to separate
chilled water from warm water returning from the load. These are the two-tank system (also called
the empty tank design), the single tank with flexible diaphragm, the labyrinth tank where water is
forced to flow through a maze (a long zigzagging channel) and the single stratified tank. The single
stratified tank is widely used as it is simple, has low cost, and its performance is comparable with
other types. In this design the warm and cold waters are separated due to density difference. A
thermocline region (a region of high temperature gradient) exists which acts as a natural barrier that
inhibits mixing between chilled and warm waters. For tanks with well-designed inlet diffusers the
thickness of the thermocline region is normally small. In U.S.A. chilled water storage constitutes
about 34% of the cooling capacity of all cool storage systems with 60% of these systems utilize
stratified thermal storage tanks as large as 15 140 m3 (4 million gallons) (Musser and Bahnfleth,
1998). A full account of the single stratified tank theory and design is given by Zurigat and Ghajar(2002). As in the above example for ice storage if 1 MW of cooling is to be stored in chilled water
the storage volume required becomes much larger than that for the ice storage. Using the figures
quoted in Hasnain (1998), i.e. 0.089–0.169 m3kWh1 the chilled water volume needed becomes
65700–124 800 m3. Unless there is an aquifer nearby it is too high a price to pay for building a tank
or system of tanks of this volume. Note that these results are for 1 MW of storage cooling capacity.
Based on the above it is seen that under the conditions investigated seasonal storage in chilled water
storage tanks or ice bins for the location considered is seen to be prohibitively expensive.
Thermal storage on diurnal basis is common and many thermal storage installations have
been in use throughout the world. The weather conditions often determine the feasibility of cool
storage as it affects the cooling load profile. It was concluded by Dincer and Rosen (2002) that
cool storage is advantageous where the summer weather profile includes limited number of peak
demand days and large temperature variations during a given 24 h period. In addition to theweather factor the load profile determines the mode of operation of thermal storage system. For
example, office buildings normally have very low cooling loads during the night as they are
unoccupied while during the day they have high cooling load which peaks in the afternoon. This
load profile is ideal for thermal storage application in full storage mode where thermal storage
fully replaces the chiller thereby eliminating the use of electricity during the day where, when
rate schedule applies, high electric charge rates exist. In hotels and residential buildings, on the
other hand, the cooling load profiles are flatter and thus they are not suitable for full storage as
the capacity in excess of the cooling load is not sufficient for charging the storage. In this case,
partial storage or peak shaving (also called load-leveling) storage modes may be employed
depending on whether electricity rate schedule is practiced by the local utilities. It is generally
recommended that cool storage be sized to meet 20% of the peak load (Dincer and Rosen,
2002). Thus, there exist mainly two modes of operation of thermal storage:
1. Operating the chillers or ice makers during the night to charge the chilled water storage
tanks or the ice bins (charge) for day use (discharge). This way, the cooling equipment
works only during the night to make use of the low off-peak electricity charge rates and
relatively cooler temperatures. This is termed full storage option.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY296
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 7/15
2. Operating the cooling equipment all the time. During the peak load, the cooling equipment
and the thermal storage work simultaneously. During off-peak or reduced cooling load
periods the cooling capacity in excess of the cooling load is stored. This is termed partial
storage option.
The second scheme is more economical in terms of investment cost as it results in smallerequipment size (Dincer and Rosen, 2002). Generally, cool storage (chilled water or ice) is
advantageous for cooling applications that have large daytime cooling loads and little or no
cooling loads at night. The next section presents the calculation results based on partial storage.
4. RESULTS AND DISCUSSIONS
As stated previously partial storage has an economic advantage over full storage, both being
applied for diurnal thermal energy storage for shaving or eliminating the peak electric demand.
The applicability of partial storage demands that the load peaks during a number of hours in the
day. A starting point in this study is to inspect the hourly ambient temperature profiles as they
are indicative of the peak air conditioning load and the peak load on electric utility thereafter. In
this work, typical meteorological year data (Zurigat et al ., 2003) were used. Figure 2 shows the
hourly ambient temperature profile for the first day of each month of the year for Fahud.
Although the profiles shown are not in magnitude representative of the temperature in the given
month but what is important here is the shape of the profile. It is seen that most profiles shown
in Figure 2 exhibit flat peaks with over 6 h duration. At first glance, similar patterns would be
Figure 2. Diurnal ambient temperature profile for the first day of each month of the year at Fahud.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 297
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 8/15
expected for the cooling load which is a favourable condition for thermal storage. One must
note, however, that the temperature profiles are indicative only of the sensible cooling load. In
hot and humid conditions the latent load may dominate the total cooling load profile. In this
study, the total hourly cooling load for gas turbine inlet air cooling was calculated as the sum of
the latent and sensible components as given by Dawoud et al . (2004).For the problem at hand, i.e. gas turbine inlet air cooling the hourly total cooling load for the
whole year was calculated by Dawoud et al . (2004) based on a design compressor inlet air
temperature of 88C. It was found that a chiller capacity of 8 MW would satisfy the cooling load
for the majority of the hours of the year. This has been estimated through a sensitivity analysis
for the impact of different chilling capacities on boosting the power of a GE frame-6B gas-
turbine unit at Fahud in Oman (Dawoud et al ., 2004).
Calculations of the mean of the daily cooling load profiles were calculated for the whole year
and showed that the maximum daily average cooling load is 7.7 MW which occurs on the 9th of
June. In technical terms the profile indicates seasonal variation which, in principle, is very
suitable for seasonal energy storage. However, the example discussed at the start of the previous
section shows that this is a prohibitively expensive endeavour. Therefore, emphasis has been
focused on diurnal thermal storage, namely the partial storage. To evaluate this option the firststep is to quantify the storage capacity needed. Recall that in partial storage scheme the chillers
operate continuously. Assume that the chiller is sized at the maximum of the mean daily cooling
load. Then, it would be ideal if the excess cooling produced by the chiller during off-peak hours
is stored and is sufficient (in conjunction with the chiller) to meet the cooling demand during on-
peak hours.
The calculated daily average cooling load profiles indicate that the cooling load peaks during
summer months and there is a distinct variation in cooling load from one day to another.
Hourly cooling load variation for some days exhibit large diurnal variation a condition essential
for the applicability of thermal energy storage. But this is not consistent as in some days the
cooling load profile exhibits flat profile (see Figure 3).
A closer look at the cooling load profiles calculated shows that most of the time the peak
period is wide in span and occupies almost 8 h in the day. In fact, for the 9th of June the profileis almost flat considering the y-axis scale (see Figure 3). The potential for thermal energy storage
is evaluated using the cooling load profiles calculated for each day. For example, for the 3rd of
July (see Figure 4) the daily average cooling load, denoted by % Qc is calculated to be 5.34 MW
while the peak cooling load for that day is 9.25 MW which is the maximum for the year. For
another day in July (see Figure 5) % Qc ¼ 6:06 MW with peak cooling load of 6.8 MW.
To see whether a chiller operating 24 h on 3rd of July at 5.34 MW capacity would satisfy the
cooling load when coupled with cool storage the hourly gas turbine inlet air cooling load profile
is plotted along with the daily mean cooling load (see Figure 4) of 5.34 MW. The (+) regions
indicate excess cooling that can be stored while the () regions indicate cooling load to be
supplied by thermal storage. Clearly, for this particular day, the (+) and () areas are equal and
in case of no thermal losses occur during charge and discharge of thermal storage, then a
5.34 MW chiller would be sufficient as opposed to 9.25 MW chiller needed to satisfy the peakcooling demand. Let us assume for now that the 3rd of July is the design day based on which the
chiller and thermal storage tank sizes are determined. For 3rd of July the cooling produced by
the chiller in excess of the cooling load is 18.52 MWh while the cooling load demand in excess of
the chiller capacity of 5.34 MW is 18.52 MWh, as expected from a chiller operating at the daily
mean cooling load. Therefore, a system consisting of 5.34 MW chiller integrated with an
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY298
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 9/15
Figure 3. Cooling load profile for the day with maximum daily average cooling load (9th of June).
Figure 4. Hourly gas turbine inlet air cooling load for Fahud on 3rd of July.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 299
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 10/15
18.52 MWh thermal storage is sufficient. Thus, a reduction in the chiller size of about 43.3% (or
3.91 MW) is achieved. This is a perfect example of the advantage of thermal storage. But, we
should remember that this is based on one specific day with a chiller sized at an average daily
cooling load. Calculations, shown later in this section, show a different conclusion. The above
figure of 18.52 MWh storage is calculated by integrating the (+) areas numerically.
The amount of cooling stored for 3rd of July (18.52 MWh) necessitates a chilled water storagetank volume of 1648–3130 m3 based on storage tank volume given by Hasnain (1998) as
0.089–0.169 m3 kWh1. If ice storage is used instead, ice bin volume of 352–426 m3 is required
based on the figures given by Hasnain (1998), i.e. 0.019–0.023 m3 kWh1. Based on the figure
quoted in Dincer and Rosen (2002), i.e. 3 kg of ice is required per MJ of cooling 200 000 kg of ice
is required or 200m3 volume. This is termed ‘min1’ in Table III below as it is the minimum size
based on the rules used to calculate the ice storage size.
To reduce the storage size one is tempted to follow the recommendation that cool storage be
sized to meet 20% of the peak load (Dincer and Rosen, 2002), i.e. 1.85 MW (0.2 9.25=1.85)
the amount of cool storage becomes 9.25 MWh assuming a time span of 5 h. Then a chilled
water storage tank volume of 735–1564 m3 or an ice bin of 176–213 m3 volume (or 100 000 kg
mass or a 100 m3 based on 3 kg ice per MJ) is required. The chiller size should be increased to
satisfy the peak cooling load when operated simultaneously with thermal storage. Trial anderror calculations based on the peak cooling load less the 9.25 MWh storage give a chiller size of
6.7 MW. If instead, 4 h duration of the peak load is assumed then a 7.5 MWh of cool storage is
required which needs 668–1268 m3 of chilled water storage volume or an ice bin of 143–173 m3
(or 81 100 kg or 81.1 m3 based on 3 kg ice per MJ) is required. A chiller size of 7 MW is needed.
These results indicate that sizing the cool storage to meet 20% of the peak cooling load results in
Figure 5. Hourly gas turbine inlet air cooling load for Fahud on July 6th.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY300
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 11/15
a reduction in the chiller size by 1 MW as 8 MW chiller will do without the need for thermal
storage (Dawoud et al ., 2004). Whether a 7 MW chiller integrated with thermal storage of
7.5 MWh cooling capacity is profitable compared with 8 MW chiller without thermal storage
can only be ascertained by economic assessment. In the absence of time-of-use utility rate
structure in Oman a simple cost comparison is shown in Table III and shows that thermal
storage under the conditions discussed above is not a viable option.It should be noted that assessments based on a single day profile may be misleading. Hence,
problem analysis should consider hour-by-hour calculations as done in this work below.
Based on the above results we may select the size of the chiller to be at the daily average
cooling load of a selected design day. The day with the max hourly cooling load may seem to be
a good selection. However, as will be seen below this is not the case and the cooling load profiles
are detrimental to the success of thermal storage application. So, fixing the chiller size at 5.34
and plotting the difference between the (+) and () areas (see Figure 6) for all the days in the
year shows that a chiller of 5.34 MW capacity would experience insufficient capacity to satisfy
the cooling load during a significant part of summer months (142 days) when cooling is most
needed. So, increasing the chiller size results in less and less number of days with negative
difference (deficit). Figure 7 shows the cumulative distribution function of the deficit for
different chiller sizes. Also, the number of days with deficit is indicated. For example,for a chiller of 6.0 MW cooling capacity there is 102 days experiencing deficit. This is indicated
on the figure as 6.0::102. Based on the results shown in Figure 7 one can find the number
of days experiencing a deficit below or above a certain value. For example, for the 6.0 MW
chiller 70% of the 102 days experiencing deficit experience deficit greater than 10 MWh
(or about 71 days).
Table III. A simple economic evaluation of cool storage for gas turbine inlet air cooling basedon 3rd of July cooling load.
Chilled water storage size (m3) Ice storage size (m3)
Cool storage
(MWh)
Chiller size
(MW) Min Max Min1/Min Max
7.5 7.0 668 1268 81/143 1739.25 6.7 735 1564 100/176 213
18.52 5.34 1648 3130 200/352 426
0.0 8.0n 0.0 0.0 0.0 0.0
Coolstorage(MWh)
Chillersize
(MW)
Chillercost in
k$ at 71$ kW1
Chilled waterstorage cost in
k$ at 18$kWh1
Ice storagecost in k$
at 17$kWh1
Totalcost k$
Ch. W./Ice
7.5 7.0 497 135 128 632/6259.25 6.7 476 167 157 643/633
18.52 5.34 379 333 315 712/694
0.0 8.0n 568 0.0 0.0 568
nWithout cool storage.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 301
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 12/15
Figure 6. Difference between storage and demand cooling load for 5.34 MW chiller.
Figure 7. Cumulative distribution of the difference between storage and demandcooling load for different chiller sizes.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY302
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 13/15
Because the deficit is experienced during summer months calculations on monthly basis are
shown in Figure 8 for a 6.0 MW chiller. The designation month (days) indicate the number of
days with deficit in the month indicated. For example, 8 (27) indicates that for a 6.0 MW chiller
integrated with thermal storage 27 days in August experience deficit. Similarly, 3 days in April
and also in October experience deficit. Clearly, August experiences the highest deficit as 70% of the 27 days (i.e. 19 days) experience deficit of over 25 MWh. The conclusion out of these results
is that higher capacity chiller (>6.0 MW) is needed if one is to satisfy the cooling load during
summer months.
In calculating the size of cool storage and the chiller size it was assumed that no thermal losses
occur. To account for the latter we note that thermal losses are of two types:
1. Heat transfer from the storage tank and piping to the surroundings. This is applicable to
both ice and chilled water storage tanks.
2. Heat losses due to blending in stratified thermal storage during charge and discharge
cycles.
If we introduce thermal storage effectiveness as the ratio of cooling recovered over cooling
stored then the thermal storage size (and the chiller as well) may be sized based on 90%effectiveness (5% loss during charge and 5% during discharge). Hence, the storage size would be
10% higher than the calculated one and the chiller size would also be higher. The chiller size of
8 MW selected for gas turbine inlet air cooling (Dawoud et al ., 2004) would do well without TES
(see also Table III). For proper sizing of both the chiller and the storage detailed dynamic
Figure 8. Monthly cumulative distribution of the difference between storage and demandcooling load for 6.0 MW chiller.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 303
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 14/15
system simulations coupled with economic assessment model would be needed. However, the
simplified analysis done in this work revealed the main characteristics of integration of thermal
storage with gas turbine inlet air cooling for a specific location where hour-by-hour cooling load
and weather data are considered. Hence, based on the results presented and the simple economic
assessment (Table III) TES is not a viable option for gas turbine inlet air cooling as it did notresult in reduction in the chiller size. The main reason behind these results is the shape of the
cooling load profiles as in any given day during summer time gas turbine inlet air cooling is
required all the time. This is in contrast with cool storage applications in commercial or public
buildings where the cooling load profiles have distinct peaks of short duration.
5. CONCLUSIONS
In this work, the thermal storage option for gas turbine inlet air cooling is assessed based on
hourly weather data and cooling load profiles for a remote oil field location (Fahud) in Oman.
The analysis is based on hour-by-hour calculations of the gas turbine cooling load using Typical
Meteorological Year data. Thermal storage capacity was calculated for different chillers sizes. Inthe absence of time-of-use utility rate structure (as in Oman) the only important parameter that
diurnal thermal storage will affect is the reduction in chiller capacity resulting in a reduction in
both the first and operating costs irrespective of the chiller type. It was found that diurnal cool
storage in partial storage mode does not result in reducing the chiller size. Also, despite the
seasonal variation in cooling load, under the conditions investigated seasonal storage in chilled
water storage tanks or ice bins for the location considered is shown to be prohibitively expensive
and thus not recommended. Thus, it is concluded that the cool storage in either ice or chilled
water forms is not viable for the considered location. Also, it must be noted that assessments of
thermal energy storage option based on a single cooling load profile proved to be misleading.
Hence, problem analysis should consider hour-by-hour calculations as done in this work.
ACKNOWLEDGEMENTS
This work is funded by the Petroleum Development of Oman (PDO) under contract No. 2002-52.
REFERENCES
Andrepont JS. 2001. Combustion turbine inlet air cooling (CTIAC): benefits and technology options in district energyapplications. ASHRAE Transactions: Symposia, Paper No. AT-01-15-4, 892–899.
Antoniak ZA, Brown DR, Drost MK. 1992. An evaluation of thermal storage options for precooling gas turbine inletair. U.S. Department of Energy Report: DE-AC06-76RLO 1830.
Bakenhus BH. 2000. Ice storage project. ASHRAE Journal 42(5):64–66.Chaker M, Meher-Homji CH. 2002. Inlet fogging of gas turbine engines: climatic analysis of gas turbine evaporative
cooling potential of international, locations. Proceedings of the ASME Turbo Expo 2002, 3–6 June, Amsterdam,The Netherlands (Paper No: GT-2002-30559).
Dawoud B, Zurigat YH, Bortmany J. 2004. Power requirements for different gas-turbine inlet air cooling technologiesand their impact on power boosting at two locations in Oman. Proceedings of the 1st Cappadocia International Mechanical Engineering Symposium, 14–16 July 2004, Cappadocia, Turkey.
Dincer I, Rosen MA. 2002. Thermal Energy Storage Systems and Applications. Wiley: New York.Hasnain SM. 1998. Review on sustainable thermal energy storage technologies. Part II: cool thermal storage. Energy
Conversion and Management 39(11):1139–1153.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
Y. H. ZURIGAT, B. DAWOUD AND J. BORTMANY304
7/23/2019 Er.1148] Y. H. Zurigat; B. Dawoud; J. Bortmany -- On the Technical Feasibility of Gas Turbine Inlet Air Cooling Utilizing
http://slidepdf.com/reader/full/er1148-y-h-zurigat-b-dawoud-j-bortmany-on-the-technical-feasibility 15/15
Hasnain SM, Alawaji SH, Al-Ibrahim AM, Smiai MS. 1999. Applications of thermal energy storage in Saudi Arabia.International Journal of Energy Research 23(2):117–124.
Musser A, Bahnfleth WP. 1998. Evolution of temperature distribution in a full scale stratified thermal storage tank withradial diffusers. ASHRAE Transactions 104(Part 1A):55–67.
Ondryas IS, Wilson DA, Kawamoto M, Haub GL. 1991. Options in gas turbine power augmentation using inlet airchilling. Journal of Engineering for Gas Turbines and Power 113:203–211.
Somasundaram S, Drost MK, Brown DR, Antoniak ZA. 1993. Coadunation of technologies: cogeneration and thermalenergy storage. Proceedings of the ASME Cogen-Turbo Conference, August 1993, Bournemouth, Ukraine, 1–12.
Stewart WE. 1998. Turbine inlet air cooling. ASHRAE Journal 40(9):32–37.Zurigat YH, Ghajar AJ. 2002. Heat transfer and stratification in sensible heat storage systems. In Thermal Energy
Storage Systems and Applications, Chapter 6, Dincer I, Rosen MA (eds). Wiley: New York, 259–301.Zurigat YH, Sawaqed NM, Al-Hinai H, Jubran BA. 2003. Development of typical meteorological years for different
locations in Oman. Final Report, Petroleum Development of Oman, Oman.
Copyright # 2005 John Wiley & Sons, Ltd. Int. J. Energy Res. 2006; 30:291–305
GAS TURBINE INLET AIR COOLING UTILIZING THERMAL ENERGY STORAGE 305