How to Use Simulation Tools to Improve Supermarkets Design and Operation Jaime Arias

How to Use Simulation Tools to
Improve Supermarkets Design
and Operation
Jaime Arias
Div. of Applied Thermodynamics and Refrigeration
Dept. of Energy Technology
Royal Institute of Technology
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Contents
1.- Introduction.
2.- CyberMart, Systems and Models.
3.- Evaluation of energy using in a supermarket.
4.- Conclusions.
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
1.- Introduction.
Energy-saving technologies as heat recovery, floating
condensing temperature, energy efficient lighting, energy
efficient display cases have been implemented in several
supermarkets.
A systems model is necessary in order to predict and evaluate
the introduction of new concepts and ideas in supermarkets.
A systems model is also necessary to compare and analyse the
real energy performance of new energy saving technologies
implemented in supermarkets.
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
1.- Introduction.
There are different ways to compare and study the energy
using in a supermarkets.
1.- Performance Indices.
Total Energy / Total Area [kWh/m2]
2.- Simulations.
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Task 2 – Development of performance
indices for supermarkets
Total energy / Total Area [kWh/m2]
Data from 146 supermarkets from ICA
Supermarkets
Total Area
0 - 600
600 - 1000
1001 - 1500
1501 - 3000
3001 - 9000
Number
21
51
29
31
14
146
Average Area
m2
463
786
1221
2066
5044
TotEner
kWh
255451
389758
560433
929026
1908686
TotEner/m2
KWh/m2
551
496
459
450
378
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Simulations
CyberMart.
CyberMart is computer program for simulation of indoor
climate in different supermarkets, where the influences
from cabinets, lighting, people, heat recovery, air
conditioning and outdoor climate are simulated.
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
The Supermarket System
System Boundaries
Electricity
Ambient conditions
District heating
Refrigeration
System
District cooling
HVAC
System
Indoor conditions
t = 22C, HR = 65%
Heat
Cabinet
System
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Main Program
System design
LCC
Outdoor
Climate
Building
Heat
Rec.
Indoor
Climate
TEWI
A.C.
Cold
Rooms
Cabinets
Pipes and
pumps
Compressor
Defrost
Brine
Evaporator
Chiller
Condenser
Expansion
Valve
Pipes and
pumps
Dry Cooler
Dry Cooler
Fluid
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
HVAC Model
AC
RHEX
mfresh
T1
X1
Outdoor
T2 T3
X2
X3
T4
X4
Re-circulation
HR
T5
AH
T6
Tsup
msup
X5
X6
Xsup
Supermarket
mrecir
T7
mout
X7
mret
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Air massflow
Outdoor Temperature
Air Cooled Condenser
UAcond.
Discharge Line
Compressor
Liquid Line
Compressor Power
Suction Line
Expansion
device
Cabinet
Cold Storage
Evaporator
Evaporator
UAevap.
UAevap.
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Completely Indirect System
Outdoor Temperature
Dry Cooler
UAdrycooler
Coolant fluid
Pump
UAcond.
Compressor Power
Chiller
UAevap.
Pump
Secondary refrigerant
UAcabinet
Cabinet
Indoor Temperature
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
3.- CyberMart
CyberMart
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Lambohov
Simulation from CyberMart
No HR or FC
HR and FC
Ventilation [MWh/year]
93
93
Lightings [MWh/year]
112
112
Equipments [MWh/year]
80
80
Heating [MWh/year]
108
30
Refrigeration System [MWh/year]
335
263
728
72100
578
57200
Total Energy Usage [MWh/year]
Energy Cost [US$/year]
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Lambohov Total Energy Usage 2006
Measurement
CyberMart
January
54193
47290
12,7%
February
46811
42449
9,3%
Mars
50733
47102
7,2%
April
50317
47062
6,5%
May
54180
50950
6,0%
June
54761
52692
3,8%
July
58830
57220
2,7%
August
56983
55113
3,3%
September
52538
51358
2,2%
Total 2006
479348
451235
5,9%
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Lambohov
Total Electricity Usage 2006
100
Out.Temp
Tot.El.Meas.
Tot.El.Cyb.
Tot.Comp.Meas.
Tot.Comp.Cyb.
07
09
Temp[°C], Power[kW]
80
60
40
20
0
-20
12
01
02
02
03
04
05
06
07
08
10
11
Time[day]
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Lambohov
20050401-20050406
50
Temp[°C], RH[%], Power[kW]
40
30
20
10
0
Out.Temp
-10
00:00
00:00
Aux.Heating
00:00
HRSuplied
00:00
HRreturn
00:00
DCsupplied
00:00
DCreturn
00:00
Time
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
5.- Conclusions
There is a great potential for improvement of energy
systems in supermarkets.
The system approach and the interconnection between the
different subsystem implemented in the program CyberMart
predict and evaluate the introduction of new concepts and
ideas in supermarkets.
A particular energy efficient solution for each supermarket
is possible to achieve only when there is a balance between
Costs, Environmental Impact and Performance
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
5.- Conclusions.
The implementation of new energy saving technologies in
supermarkets requires an extensive analyse of energy
performances.
This analysis should be done during a long period to evaluate
and compare the real energy performance with the theoretical
values calculated.
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Total Energy Usage from Compressors 2006
Measurements
CyberMart
Procent
Jan
17018
13349
21,6%
Feb
14132
11838
16,2%
Mar
13951
13121
6,0%
Apr
14537
13794
5,1%
May
17519
15694
10,4%
Jun
18840
18014
4,4%
Jul
21178
21070
0,5%
Aug
19269
19224
0,2%
Sep
17138
16528
3,6%
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Building Model
Heat Balance room air
Heat gains to room air – Heat losses from room air = 0
Qcon – Hv * (Ts – Tr ) – Hw * (Tr – To ) – Hc * (Tr – Ts ) – Qg=0
where
Qcon = Qsol. + Qp.+ Qeq. + Ql. - Qcabcon
Hw : Specific loss from room air to outside W/K
HV : Specific loss from room air to ventilation air W/K
Hc : Specific loss from room air to room surfaces W/K
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Heat Balance room surfaces
Heat gains to room surfaces – Heat losses from room surfaces = 0
Qrad + Hc * (Tr – Ts ) – Hac * (Ts – Tac ) = 0
where
Qrad = Qsol. + Qp.+ Qeq. + Ql. - Qcabrad
Hac : Specific loss from room surfaces to structure W/K
Hc : Specific loss from room air to room surfaces W/K
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Heat Balance building structure
Heat gains to structure - Heat losses from structure = Accumulated heat in
structure
Hac*(Ts – Tac ) – Hout*(Tac – To ) = CA*dTS /dt
where
CA : Total heat capacity of the room
dTS : Variation of structure temperature
dt : time period
Hac : Specific loss from room surfaces to structure
Hout : Specific loss structure to outside
Wh/°K
°C
h
W/K
W/K
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
The equivalent outdoor temperature
Te = Tout + (Isol αsol + (Tsky – Tout ) *αr )/ αe
Where:
Tout : Outdoor temperature
Tsky : Sky temperature
αsol : Absorptivity for solar radiation
αr : Radiative heat transfer coefficient
αe : Effective heat transfer coefficient
αe = αr + αc
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Description of calculation
1. Assumption of temperatures before cabinets and dry cooler
2. Calculation of evaporating and condensing temperature
Q2
T2 = Tbrinein −
εevap ⋅ m brine ⋅ cpbrine
T1 = Tcoolantin +
Q1
εcond ⋅ m coolant ⋅ cpcoolant
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Condenser and Evaporator
The effectiveness of the condenser and evaporator are defined as
ε = 1 − e (− NTU )
NTU is the number of transfer unit defined for the evaporator as
NTU evaporator =
UAevaporator
m air ⋅ cpair
And for the condenser as
NTU condenser
UAcondenser
=
m air ⋅ cpair
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Pressure drops and pumps
The pressure drop
f1 ⋅ ρ ⋅ w 2 ⋅ L
Δpf =
d
The friction factor
f1 =
1
( 0 .7 9 ⋅ l n ( R e ) − 1 .6 4 )
f1 =
32
Re
2
Turbulent flow
Laminar flow
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Pressure drops and pumps
The pressure drop in evaporator and condenser
Δphex =
2 ⋅ f ⋅ N p ⋅ m 2 ⋅ L
ρ ⋅ de
The pressure drop in cabinets
Δpcab
f1 ⋅ ρ ⋅ w2 ⋅ L
=
d
The pump power
Δptot ⋅ V
Pp =
η pump
Where
Δptot = Δpcab + Δphex + Δptube
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Condenser and Evaporator
The effectiveness of the condenser and evaporator are defined as
ε = 1 − e (− NTU )
NTU is the number of transfer unit defined for the evaporator as
NTU evaporator =
UAevaporator
m brine ⋅ cpbrine
And for the condenser as
NTU condenser =
UAcondenser
m drycoolerfluid ⋅ cp drycoolerfluid
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Dry Cooler
The effectiveness of the counter flow heat exchanger
ε=
1 − e (− NTU ⋅(1−Cr )
1 − C r ⋅ e (− NTU ⋅(1−Cr )
NTU is the number of transfer unit defined for counter flow heat exchanger as
NTU HEX =
UAHEX
C min
Cold heat capacity rate
Cc = m c ⋅ cpc
Hot heat capacity rate
C h = m h ⋅ cph
Heat capacity ratio
C min
Cr =
C max
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Compressor 2N-5.2Y
13,8 kW
30
40
50
-15
14,8
12,5
9,9
-10
18,5
15,7
12,7
-5
22,7
19,5
15,9
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Lambohov
20050401-20050406
50
Temp[°C], RH[%], Power[kW]
40
30
20
10
0
Out.Temp
-10
00:00
00:00
Aux.Heating
00:00
HRSuplied
00:00
HRreturn
00:00
DCsupplied
00:00
DCreturn
00:00
Time
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Comparison Measurement - CyberMart
Supermarket in Täby Centrum during one Year
Temp[°C], RH[%], Power[kW]
110
90
70
50
30
10
-10
-30
12
01
03
Out.Temp.Meas.
Out.Temp.Cyb.
Comp.Pow.Med. Meas.
Comp.Pow.Med. Cyb
05
06
08
10
11
01
Time
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Comparison Measurement - CyberMart
Supermarket in Täby Centrum during one Year
70
Temp[°C], RH[%], Power[kW]
60
50
40
30
20
10
0
-10
-20
Ind.Temp.Meas.
Out.Temp.Meas.
Ind.Temp.Cyb.
Out.Temp.Cyb.
RH.Meas.
RH.Cyb.
-30
12
01
03
05
06
08
10
11
01
Time
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Comparison Measurement - CyberMart
Supermarket in Täby Centrum one Year with same climate data
70
Temp[°C], RH[%], Power[kW]
60
50
40
30
20
10
0
Ind.Temp.Meas.
Out.Temp.Meas.
RH.Meas.
-10
-20
Ind.Temp.Cyb.
Out.Temp.Cyb.
RH.Cyb.
-30
12
01
03
05
06
08
10
11
01
Time(day)
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Comparison Measurement - CyberMart
Supermarket in Täby Centrum one Year with same climate data
Temp[°C], RH[%], Power[kW]
110
90
70
50
30
10
-10
Out.Temp.Meas.
Comp.Pow.Meas
-30
12
01
03
05
06
Out.Temp.Cyb.
Comp.Pow.Cyb
08
10
11
01
Time(day)
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden
Jaime Arias
Dept. of Energy Technology
Royal Institute of Technology
Sweden