General composition of the concrete which constructed THSR (Taiwan High Speed Rail):
• Cement : 330 kg /M3
• Aggregate : 1050kg /M3 ( ψ 3/ 8” :66.6% and ψ 3/ 4” :33.4%; all with 1% hydrous ratio)
• Sand : 870kg /M3 (with 8% hydrous ratio)
• Water : 160kg /M3 (only 80kg /M3 need to be added by considering the water contained in aggregate and sand).
• ADM : 7kg /M3
Estimated efficiency of various processes adopted to decrease the temperature of premixed concrete:
• Ice Water
Removable Heat Q = M x C x D T
M = weight of iced water = 80kg /M3
C = specific heat of water = 1Kcal/kg ℃
D T = temperature difference = original water temperature 25 ℃ – ice water temperature 1 ℃ = 24 ℃
Q1 = 80kg /M3 x 1Kcal/kg ℃ x 24 ℃ = 1920Kcal/M3
Temperature Descent of 1 CBM concrete D T1 = 1920/628.1 = 3.06 ℃
• Chilling Small Gravel (aggregate of ψ 3/ 8” )
Removable Heat Q = M x C x D T
M = weight of small gravel aggregate = 1050kg /M3 x 66.6% = 700g /M3
C = specific heat of gravel aggregate = 0.23Kcal/kg ℃
D T = temperature difference = original gravel aggregate temperature 28 ℃ – cooled gravel aggregate temperature 10 ℃ = 18 ℃
Q2 = 700kg /M3 x 0.23Kcal/kg ℃ x 18 ℃ = 2898Kcal/M3
Temperature Descent of 1 CBM concrete D T2 = 2898/628.1 = 4.61 ℃
• Chilling all Gravel Aggregate
Removable Heat Q = M x C x D T
M = weight of gravel aggregate = 1050kg /M3
C = specific heat of gravel aggregate = 0.23Kcal/kg ℃
D T = temperature difference = original gravel aggregate temperature 28 ℃ – cooled gravel aggregate temperature 10 ℃ = 18 ℃
Q3 = 1050kg /M3 x 0.23Kcal/kg ℃ x 18 ℃ = 4347Kcal/M3
Temperature Descent of 1 CBM concrete D T3 = 4347/628.1 = 6.92 ℃
• Ice Water + Chilling all gravel Aggregate
Q4 = Q1 + Q3 = 1920 Kcal/M3 + 4347Kcal/M3 = 6267Kcal/M3
Temperature Descent of 1 CBM concrete D T4 = 6267/628.1 = 9.98 ℃
Estimated electricity consumption and cost:
Conditions: 1). Daily output 1000CBM ( 8 hours a day, 25 days a month in summer.)
2). Based on the rate of 380V industrial power of Taiwan Power Company.
A. Regular Contracted Demand: a. Summer (Jan.~Sep.):NTD213/HP/month
b. Non-summer: NTD159/HP/month
B. Rate per KwHr: a. Peak period ( 10:00 ~ 12:00 , 13:00 ~ 17:00 ): NTD2.95
b. Off-peak period ( 22:30 ~ 07:30 ): NTD0.7
c. The other time: NTD1.75
• Ice Water : 125HP(93.75Kw) Ice Water Chiller, estimated power cost per CBM
A1. Monthly rent share: NTD213/HP/month x 125HP/25day/month/ 1000M3 /day
= NTD1.065/M3.day
B1. Share per KwHr: NTD0.7/KwHr x 9Hr/night x 93.75Kw/ 1000M3 /day
= NTD0.591/M3.day
Total unit cooling cost P1 = A1 + B1 = NTD1.065 + NTD0.591 = NTD1.656/M3.day
• Chilling Small Gravel (aggregate of ψ 3/ 8” ) : 75HP(56.25Kw) Cold Air Chiller
A2. Monthly rent share: NTD213/HP/month x 75HP/25day/month/ 1000M3 /day
= NTD0.639/M3.day
B2. Share per KwHr: (NTD2.95/KwHr x 6Hr + NTD1.75/KwHr x2Hr) x 56.25Kw / 1000M3 /day = NTD1.193/M3.day (Daily work period: 09:00 ~ 17:00 )
Total unit cooling cost P2 = A2 + B2 = NTD0.639 + NTD1.193 = NTD1.832/M3.day
• Chilling all Gravel Aggregate : 150HP(112.5Kw) Cold Air Chiller
A3. Monthly rent share: NTD213/HP/month x 150HP/25day/month/ 1000M3 /day
= NTD1.278/M3.day
B3. Share per KwHr: (NTD2.95/KwHr x 6Hr + NTD1.75/KwHr x2Hr) x 112.5Kw / 1000M3 /day = NTD2.385/M3.day (Daily work period: 09:00 ~ 17:00 )
Total unit cooling cost P3 = A3 + B3 = NTD1.278 + NTD2.385 = NTD3.663/M3.day
• Ice Water + Chilling all Gravel Aggregate : 125HP Ice Water Chiller + 150HP Cold Air Chiller
Total unit cooling cost P4 = B1 + P3 = NTD0.591 + NTD3.663 = NTD4.254/M3.day
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