Hướng dẫn các tính chọn và thiết kế máy Heating water Midea
7. Application
7.1. Daily Consumption, Temperature and Quality of Hot Water
7.1.1, Daily consumption
No. | Type of building | unit | Max. daily consump tion per day (L) | Usage time(hour) |
1 | residence With self-supply heating water and bath equipment | Daily per person | 40~80 60~100 | 24 |
2 | Villa | Daily per person | 70~110 | 24 |
3 | Students’ dormitory, training room, ordinary hotel, etc. With public cloakroom With public cloakroom and bathroom With public cloakroom, bathroom and clothes-washing room With separate toilet and clothes-washing room | Daily per person Daily per person Daily per person Daily per person | 25~40 60~60 50~80 60~100 | 24 hours or fixed time |
4 | Guest room of hotel Guest Staff | Daily per bed Daily per person | 120~160 40~50 | 24 |
5 | In-patient department of hospital With public cloakroom With public cloakroom and bathroom With separate toilet and clothes-washing room Medical workers Out-patient department, dispensary Sanatorium | Daily per bed Daily per bed Daily per bed Daily per bed Daily per bed | 60~100 70~130 110~200 70~130 7~13 100~160 | 24 |
8 | ||||
24 | ||||
6 | Geracomium | Daily per person | 50~70 | 24 |
7 | Kindergarten and baby farm In residence No | Daily per child Daily per child | 20~40 10~15 | 24 10 |
8 | Public Bathhouse Shower Bath, tub Sauna (bath and massage) | per person every time Daily per person Daily per person | 40~60 60~80 70~100 | 12 |
9 | Hairdressing, beauty parlor | Daily per person | 10~15 | 12 |
10 | Clothes-washing room | Per kg dry clothes | 15~30 | 8 |
11 | Dietetic place Restaurant Fast food, students’ and employees’ dinning room. Taproom, coffee house, Kara okay room | One time per person | 15~20 7~10 3~8 | 10~12 11 18 |
12 | Office building | Daily per person | 5~10 | 8 |
13 | Gymnasium | Every time per person | 15~25 | 12 |
14 | Sports centre Shower for athlete | Every time per person | 25~35 | 4 |
15 | Meeting room | Every time per seat | 2~3 | 4 |
7.1.2?sanitary ware
No. | Type of sanitary ware | Once water consumption (L) | Hourly consumption (L) | Water temperature of use (?) |
1 | Residence, hotel and villa Tub with shower apparatus Tub without shower apparatus Shower apparatus Washbowl, | 150 125 70~100 3 - | 300 250 140~200 30 180 | 40 40 37~40 30 50 |
2 | Rest house, group room, training centre. With shower room Without shower room Washstand | 70~100 - 3~5 | 210~300 450 50~80 | 37~40 37~40 30 |
3 | Dietetic place Washing pan or pool Washbowl: for staff For customer Shower device | - 3 - 40 | 250 60 120 400 | 50 30 30 37~40 |
4 | Kindergarten and baby farm Bath tub:Kindergarten Baby farm Shower device:Kindergarten Baby farm Washstand Washing pan or pool | 100 30 30 15 15 - | 400 120 180 90 25 180 | 35 35 35 35 30 50 |
5 | Hospital, dispensary, sanatorium Washing pan Washbowl Tub | - - 125~150 | 15~25 300 250~300 | 35 50 40 |
6 | Public Bathhouse Tub Shower device: With shower room Without shower room Washbowl | 125 100~150 - 5 | 250 200~300 450~540 50~80 | 40 37~40 37~40 35 |
7 | Office building, washbowl | - | 50~100 | 35 |
8 | Hairdressing, beauty parlor, washbowl | - | 35 | 35 |
9 | Laboratory Washbowl Lavabo | - - | 60 15~25 | 50 30 |
10 | Theatre Shower device Washbowl foe actor (actress) | 60 5 | 200~400 80 | 37~40 35 |
11 | Sports centre | 30 | 300 | 35 |
12 | Living room of factory and enterprise shower:Ordinary workshop Dirty workshop Wash pan: ordinary workshop Dirty workshop | 40 60 3 5 | 360~540 180~480 90~120 100~150 | 37~40 40 30 35 |
13 | Body cleaner | 10~15 | 120~180 | 30 |
7.1.3. Sanitary index of the life hot water quality
It should be conform to the current
7.1.4. Raw water treatment
The raw water solution of integrated hot water supply system should be confirmed according to comparison of many economic and technical factors such as e the quality, temperature, structure and requirement of heating device, etc.
(1) For washing room, if the daily consumption of washing room is more than 10m3 and the total hardness (calcium carbonate) of raw water is larger than 300mg/L, it should be soften. If the total hardness (calcium carbonate) of raw water range from 150 to 300mg/L, it is recommended to be soften.
(2) For other location, if the daily consumption of washing room is more than 10m3 and the total hardness (calcium carbonate) of raw water is larger than 300mg/L, it is recommended to be softened or stabilization treated. The range of total water hardness after softening should be within: 1) washing room, 50~100mg/L 2) other location: 75~150mg/L.
(3) Stabilization treatment should accord to the hardness, temperature, time of treating or effective span and work voltage hence to select physical treatment or chemical stabilizer treatment.
(4) If the system requires a high-degree of dissolved oxygen controlling, it is recommended to adopt oxygen eliminating measure.
7.1.5. Calculating temperature of cold water.
The calculating temperature should be confirmed according to the mean temperature data of local coldest water.
7.1.6. Maximum outlet temperature and minimum temperature of water distribution.
They can be selected in the following table,
Water treating condition | The maximum outlet temperature of Boiler, heating water system or water heater(℃) | Minimum temperature of distribution(℃) |
Unnecessary to soften the raw water, but raw water need to treat and had been treated. | 75 | 50 |
Raw water need to treat but haven’t been treated. | 60 | 50 |
Remark: when the supplying system just provide hot water for bath and washstand, not washing pan and pool, the distribution temperature should not be less than 40℃。
7.1.7. Selection of tank capacity:
Residence, hotel, hospital (Out-patient department, dispensary)
(1) Supply hot water all day and night
Peak-time water consumption (design hourly consumption)
Peak-time 3~4hours
Variation co efficiency K of peak-time
Style of building | Quantity of residence person for residence, hotel, quantity of beds for hospital | |||||||||||||
35 | 50 | 60 | 75 | 100 | 150 | 200 | 250 | 300 | 450 | 500 | 600 | 900 | 1000 | |
Residence | 6.58 | 5.12 | 4.49 | 4.13 | 3.38 | 3.7 | 3.28 | 2.86 | ||||||
Hotel | 9.65 | 6.84 | 5.61 | 4.97 | 4.58 | 4.19 | ||||||||
Hospital | 7.62 | 4.55 | 3.54 | 2.93 | 2.6 | 2.23 | 1.95 |
Peak-time hourly consumption:
Qr= k*Qtotal /24
Total consumption in peak time:
Qpeck =4*Qr
Suppose the peak period is 4 hours.
Available capacity of tank Q (Available capacity means the total capacity under the highest level)
Qavailable=Qpeck--4* Qunit
(2)Tank selection for part-time supply
h stands for supplying period and Qtotal means total water consumption.
Qtank=Qtotal --h* Qunit,
Because of the heat-pump heating theory, when in low ambient temperature, the heating capacity will decrease. For the sake of supplying sufficient hot water, we recommend to set auxiliary electric heater. (It will automatically start when the ambient temperature is too low.)
For MGH-F35W/S it should match electric heater of 10KW.
For MGH-F17.5W/S(N2) it should match electric heater of 5KW.
7.2. Hydraulic Calculation
After selecting the main water pipe it is necessary to do the hydraulic calculation. If the resistance of waterside is more than the selected pump head, a larger pump should be replaced. Or choose the water pipe with larger diameter.
For the detailed calculating course please refer to the relevant technical book and standard.
The following is about the application of Hazen-Williams formula:
According to relevant water supply and sewerage design criterion, calculate the resistance by Hazen-Williams formula.
According to the national standard, the resistance loss is calculated as follows:
I=10.5C-1.85dj-4.87Q1.85
(Hazen-Williams formula)
In the formula, i —head loss of pipe per unit length,m H2O/ m; Q —flow volume,m3/s; dj —inner diameter, m; C —Hazen-Williams factor, seen in the following table
Condition Type | New | Has been used for 25 years | Has been used for 50 years |
PVC | 150 | 150 | 140 |
Galvanized steel | 150 | 130 | 100 |
Cast iron | 130 | 110 | 90 |
Take cast iron pipe for example, according to the calculated velocity and resistance loss, select proper water pump and dia. of pipe.
Cast iron pipe | ||||
Dia. | Flow | Velocity | Resistance | |
mm | L/S | m/s | mm/m | |
100 | 5.00 | 0.65 | 9.02 | |
125 | 20.00 | 1.66 | 39.24 | |
150 | 25.00 | 1.43 | 24.25 | |
200 | 30.00 | 0.96 | 8.30 | |
250 | 80.00 | 1.64 | 17.14 | |
300 | 80.00 | 1.14 | 7.03 | |
350 | 140.00 | 1.46 | 9.33 | |
400 | 200.00 | 1.60 | 9.41 | |
450 | 230.00 | 1.45 | 6.86 | |
500 | 400.00 | 2.05 | 11.43 | |
600 | 500.00 | 1.77 | 7.10 | |
700 | 600.00 | 1.56 | 4.69 | |
800 | 800.00 | 1.60 | 4.17 | |
900 | 1000.00 | 1.58 | 3.55 | |
1000 | 1100.00 | 1.40 | 2.53 |
Remarks:
When the dia. ranges DN15~20 the velocity should be limited to 1.0m/s
When the dia. ranges DN25~40 the velocity should be limited to 1.2m/s
When the dia. ranges DN50~70 the velocity should be limited to 1.5m/s
When the dia. equal or over DN80 the velocity should be limited to 1.8m/s, or else the figure is italic.
7.3. Sample Project:
7.3.1, Main introduction
(1) Present status and specification
Supply hot water for a three star hotel. According to the data supplied by first party, there’re 168 sets of guest rooms and peak number of people is 250. Location city is Foshan in Guangdong province, PRC.
This project should think about the connection of water heating device, water storage, and electric control system and power supply pipe and between them.
(2) Weather data
According to the statistics data of latest 40 years by Chinese National Meteorological Centre, the meteorological data of Foshan is as follows: outdoor design temperature is 33.5℃, annual average water temperature is 20℃, and average water temperature in the three months of winter is 16℃.
7.3.2. Design standard
The project should conform to the national water supply and sewerage work and design standard. Also it should base on the local meteorological data.
7.3.3. Parameter design basis
The design parameters should base on relevant technical manual as well as the requirements, such as water temperature, supplying period, local climate, habits and custom, etc. Hence to confirm the water volume of central hot water supplying system.
7.3.4. Water consumption calculation
For quest room, the hot water consumption is about 120~160L daily per person. Considering the affluence of heat source, we choose 120L daily per person as index. So the total consumption is 250*120L=30000L per day. For this project the water demand is about 30ton per day (temp. is 60℃)
Hence the required quantity of heat is: Quantity of heat (Kcal)=specific heat of water (Kcal/Kg·℃)*temperature difference (℃)*daily consumption (Kg)
Q =1*(60-20)*30000=1200000(Kcal)
7.3.5. Select the main unit
(1) According to the calculated result and actual situation, we choose the model MGH-F35W/S, maximum power input is 9.0kw, heating capacity is 35kw, rated hot water output is 660~1200L/H (because of the change of outdoor temperature, the output will have some change. Under the worst condition it can insure to produce hot water 660L/H and average output is 850L/H, for more details, PLS refer to the technical manual of the Air-source Heat-Pump Heating Water System.)
(2) Quantity of units’ calculation. The design requires the system operate for less than 14h under standard work condition and operate for less than 18h when under worst condition. Suppose the average daily working time is 14 hours, 1200000÷(35860×14)=2.8(units), hence we choose 3 units.
7.3.6. Select the tank
The total daily consumption is 30000L; simultaneous usage factor of guest room is about 0.6.
Peak-time 3~4hours
(1) Peak-time hourly consumption:
Qr= k*Qtotal /24
Qr= 5.5*30 /24=6.875 ton
(2) Total consumption in peak time
Qpeck =4*Qr (Suppose the peak period is 4 hours.)
Qpeck =4*6.875=27.5 ton
(3) Available capacity of tank Q (Available capacity means the total capacity under the highest level)
Qavailable=Qpeck--4* Qunit
Qavailable=27.5-4*(3*0.85)=17.3 ton
(4) It is recommended to select tank of 18 ton capacity.
(5) Other (just recommendation, not standard)
a. Inner structure: stainless steel board
b. Insulated layer: foamed polyurethane.
c. Outside protective layer: stainless steel
d. Holder for tank: groove steel or double-T steel.
Remark: the placement of tank should consider the load of architecture.
7.3.7. Drawing of the project
7.3.8. Comparison with Diesel Oil Boiler:
HEATING MODE | Diesel Oil Boiler | Midea air source Water Heating System |
Energy resource | Diesel Oil | Electricity |
Combustion value | 10200 kcal/kg | 860 kcal/h |
Efficiency | 75% | 420% |
Daily water consumption | 30.0 ton(60℃) | |
Average temperature increase | 20℃~60℃ | |
Quantity of heat absorbing | 30.0T×(60℃-20℃)×1000kcal/T℃=120,000,000 kcal | |
Daily fuel consumption | 156.9kg | 332.2kwh |
Unit price of fuel | 4.3CNY/kg | 1.0CNY/kwh |
Daily operation cost | 564.8CNY | 332.2CNY |
Annual operation cost | 206152CNY | 121253CNY |
Danger | Medium | No harm to people |
Noise | Noisy | A little |
Pollution | Medium | No harm to environment |
Comparison | Large floor area, special room for boiler, pay for the worker, fee of annual inspection, etc. | Small floor area, outdoor installed and auto control. |
Remark: The comparison based on the energy price in China:
Commercial Electricity=0.13USD/kW h,
Diesel oil=0.52USD/L, LPG=1.23USD/cbm (the exchange rate in Sep. 2006 is 1 CNY = 0.125 USD)
Comparing with Diesel Oil Boiler, Heat Water Heat Pump System has the advantages of high efficiency, low expense, safe, environment protecting, low maintenance expense, etc. It can save the operation cost by about 50% per year.
7.3.9. Comparison with solar water heater
Feature of solar energy heating water system | Feature of air resource heating pump heating water system |
1. No operation cost when in sunny days, but during other days it should use auxiliary electric heater completely. Take Guangdong Province as example, as the weather data shows, there is sunlight in 240 days of one year. But in the other 125 days the energy consumption of electric heater is equal to 562 days (125*4.5=562, COP of heating water system is 4.5) consumption of heat pump water heating system. | 1. The annual operation cost of heating water system is lower than solar. The cost is about 75% of solar energy heating water unit, also it is auto control system. |
2. The water quality is not good. For the solar water heater it adopts copper-aluminum composite material, bad secondary pollution. | 2. Good water quality. It adopts stainless steel heat exchanger, conforming to the food-grade sanitary condition. |
3. Large floor area. On average the heat I square meter absorb can heating about 60L water daily. Hence if the demand is 19.6 ton it need heat absorbing board 326 square meters. | 3. Small floor area. To produce 19.6 ton hot water it just needs one unit which floor area is only 4 square meters. |
4. Large investment cost. The power of auxiliary electric heater is 10 times than heat pump water heating system. | 4. Power input of one unit is less than 10kw. |
5. Sunlight in winter is always bad but good in summer. The actual situation is: hot water demand in summer is less in winter; further the required temperature is higher. | 5. it can be set the outlet temperature according to the demand of different seasons. Much more energy-saving. |
7.3.10、Installation
No. | Accessories | Function |
1 | Filter | Filtrate the dust or impurity of heat-exchanger |
2 | Check valve | anti-water hammering, protect the pump |
3 | Hydraulic pressure gauge | Debugging and maintenance |
4 | Soft connection | Decrease vibration |
5 | Main unit | Supply caloric to heat the water |
6 | Insulated tank | Storage hot water |
7 | Blow down valve | Eliminate the dirty water after washing the tank |
8 | Water pump | Supply the water of tank to the terminal of whole system. Force certain pressure and circulate the cold water to be reheated. |
9 | Pressure switch | Confirm according the resistance of worst cycle and demand pressure of user hence control the ON/OFF of pump. |
10 | Temperature switch | Could be set according to the customer demand. Default is conducting when temp. lower than 35 ℃ and disconnecting if temp. over 42℃. To control ON/OFF of water pump and electromagnetic valve |
11 | Electromagnetic valve | Controlled by temperature switch |
12 | Ball valve | For maintenance |
7.3.11、Construction introduction
1) Dimension of tank: confirm the diameter and height of tank(according to the bearing ability of floor)
2) Diameter of water pipe: confirm the diameter and variable-diameter according to the flow volume and velocity
3) Water pump: confirm the pump head and flow
4) Thickness of insulated layer: confirm the thickness of insulated layer according to the material, heat loss.
5) Elbow: confirm according to the drawing supplied by party A
6) Supporter for tank: confirm the shape and size
7) Drawing: Such as water system and piping collocation
7.3.12、Present operation status
Since the completion of project and Up to now, it is still in a good working order. Party A also gives a high opinion of this project and Midea heating water system for the reliable quality and economical performance.
Hướng dẫn các tính chọn và thiết kế máy Heating water Midea
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