Application of heat pump hot water unit in swimming pool (2)

2. The heat pump to recover the swimming pool wet air heat practices

Heat pump technology based on the general heat pump water heater can be used for a variety of swimming pool heating and heating. The "air-conditioner-hot water unit" and "dehumidification-hot water unit" that make use of the indoor air heat (latent heat + sensible heat) in the swimming pool can also achieve "one machine dual use" and "one machine, three uses" The same time, to improve the swimming pool indoor air space environment, to wet cooling purposes. Here are three examples.

2.1 United States CRISPAIR company "E-Tech PHD" indoor heated swimming pool super energy-saving hot water air conditioning system (see Figure 2)


Figure 2 indoor heated swimming pool with hot water air conditioning system

The host absorbs the indoor water vapor and hot air latent heat and sensible heat in the warm water pool, and transfers the heat to the swimming pool to heat the water through the air-cooled heat pump to keep the water temperature constant; at the same time, the indoor air of the swimming pool is dehumidified and cooled , And fill in some fresh air, into the room to ensure the indoor air quality and non-condensing.

Its host internal processes and components can be seen in Figure 3. The system can effectively reduce 2/3 swimming pool indoor air cooling costs; 3/4 pool heating costs; 3/4 of the indoor air dehumidification costs, the system's energy efficiency COP = 3. The host heats and reheats the air through the heat pipe (adjusts the dew point); performs double dehumidification on the indoor air - the dehumidification at the cold end of the heat pipe and the dehumidification in the heat pump evaporator. Drain away part of the return air, fill some of the fresh air must be indoor staff. Fresh air volume with dew point controller adjustment.


Figure 3 hot water air conditioning heat pump system internal processes

2.2 France private indoor swimming pool with "heat pump dehumidifier - hot water unit"

This unit is mainly for dehumidification, while part of the heat transferred to the heated pool of water. Foreign data show that the production of private swimming pool wet: water area per square meter 0.10-0.15kg / hm 2 , plus 0.40-0.50kg / h per person. The water vapor generated per square meter of water is about 1t per year, and the equivalent heat per ton of water vapor is about 700KW.h. The amount of ventilation required for dehumidification is about 25-40 m 3 / m 2 .h. Heat pump dehumidification heating process can be drawn from the hd diagram (see Figure 4).

The conventional dehumidification, indoor air state point P (assuming 28 ℃, φ = 50%) is mixed with fresh air point A (assuming +5 ℃, φ = 90%), mixing point M, φ = 13%), the heat required for the heating process is Q C ; dehumidification of the heat pump, as the heat pump to draw the heat of the P state of the air, the air temperature dehumidification to K point (assuming 10 ℃, φ = 80% Heat the air heated to point E (air supply state), the heat gain of the air is (h E -h K ) × V γ = Q hp . Let the heat pump energy efficiency COP = 3.8, then the actual heat pump power consumption is only 0.263Q hp . If Q hp > Q C , then the heat pump heating in addition to heating the air, but also can have extra heat; to heat the pool water.


Figure 4 dehumidification process in the hd diagram

Foreign statistics show that the approximate annual electricity consumption of some private indoor swimming pools completely heated by electric heat pumps is shown in Table 4.

Table 4

Swimming pool electricity situation

Single glazing

Double glazing

Small glass window

1

2

3

1

2

3

1

2

3

Fast water heater. Heated seats * , siding heating * , underfloor heating * , and heat in the bathroom

( 2 pool area)

1000

1500

2200

600

900

1800

200

400

1200

Small heat pump units, water circulation pumps, lighting and other power consumption

( 2 pool area)

800

900

900

800

900

900

800

900

900

Total indoor pool power consumption

( 2 pool area)

1800

2400

3100

1400

1800

2700

1000

1300

2100

Note: 1-unit residential indoor swimming pool; 2- apartment with indoor swimming pool; 3- hotel with indoor swimming pool.

* - These figures are equally valid for heating seats, siding heating, and floor heating.

Dehumidification - heat pump with heat pump unit circulation and composition shown in Figure 5. The unit has two separate refrigerant circuits - two heat pumps: one for air-air and one for air-water. The compressor section of the first heat pump is responsible for the dehumidification of the indoor air in the pool while reheating the dehumidified air with an air-cooled condenser. If a single heat pump can not reach a predetermined amount of dehumidification, then start the second heat pump compressor to complete the rest of the dehumidification. However, the condenser of the second heat pump is of copper-controlled water-cooled type and heats the recovered heat to heat the pool water. Control the amount of fresh air into the minimum, in order to save energy, no fresh air at night, completely using indoor air circulation. When the amount of dehumidification is reduced (meaning less heat absorption, the heat of condensation on the air is reduced), an auxiliary heater is used to heat the air to ensure that indoor heating needs.


Figure 5 dehumidification - heat pump unit

2 .3 DRY-O-TRON brand indoor swimming pool, jacuzzi, small commercial climate and energy regeneration system at DECTRON Canada - To reduce indoor air quality and ensure dehumidification without condensate - hot water unit

By recycling the water vapor evaporated from the pool to the air, the heat is recovered to heat the pool of water and also return the air to the heat. On the other hand, by reducing the air temperature to the dew point, the water vapor condenses into water and dries Air, to achieve the effect of dehumidification, but also the recovery of evaporated water, and then back to the pool, reducing the pool of make-up water, so as to achieve a constant temperature, humidity, energy saving, water saving, environmental protection effect. The system flow chart can be seen in Figure 6.


Figure 6 pool energy regeneration system

3. Heat pump hot water unit for swimming pool program and its economy

3.1 process and control

The currently recommended heat pump hot water unit for the swimming pool heating system process shown in Figure 7.


Figure 7 heat pump hot water unit for the pool heating process flow chart

In the process, the hot water above 55 ° C in the open storage tank A is pumped into the water separator with a pump, all the way from the water separator to the reheater of the pool water, and the indirect circulation of the heated pool water. Set the water temperature of 27 ℃, the extracted water from 24 ℃ to 28 ℃, return to the pool. While the other way as a heating source of replenishment heating, mixed with tap water through a water mixer, become 28 ℃ water into the balance tank, the balance of the pool level and the pool water surface at the same height, once the pool level drops, the balance pool The water level also dropped through the float valve on the 28 ° C water supplement pool. The third way is to shower shower shower, the use of dry pipe cycle, unused hot water cycle back to the regenerative tank B, reheated by the host inhalation.

3.2 design calculations and steps

3.2.1 Known conditions:

1) Swimming pool capacity: 300m 3

2) shower and other daily hot water and temperature: 6750 liters (55 ℃)

3) The temperature of the pool water and the indoor temperature of the swimming pool: the temperature of the pool water is 27 ℃ and the room temperature is 28 ℃.

4) Average local air temperature: 23 ℃ in spring and autumn (March-May and September-November), 28 ℃ in summer (June-August) and 15.37 ℃ in winter (December-February)

5) extreme maximum temperature of 38.7 ℃; extreme minimum temperature of 0.2 ℃

6) local tap water temperature (average): 15 ℃ in winter, 17.5 ℃ in spring and autumn, 20 ℃ in summer and 10 ℃

3.2.2 heat load calculation

1) one-time impact load (initial filling or changing water)

Should be calculated in winter conditions, tap water temperature to take the lowest value: 10 ℃; water cycle 24-48 hours, the case take 48 hours. P 2h = 1.15 × V × (t 2 -t 1 ) × 1000 / (860 × 48) = 1.15 × 300 × (28-10) × 1000/860 × 48 = 150.44 kw

2) daily load:

(1) to make up for the heat loss load: when the water temperature is 27 ℃ and the room temperature is 28 ℃, the water quantity per square meter of cooling water is 372W / m 2 ; the hourly cooling load P h1 = 200 × 372/1000 = 74.4kW; daily cooling load Q h1 = 74.4 × 24 = 1785.60kWh

(2) Replenishment heat load: The daily recharge volume of 5% of the pool volume, the winter conditions when the cold water temperature is 15 ℃, the hour recharge heat load P h2 = [V × B × 1000/24 ​​× (t 2 -t 1) /860×0.95] = 300 × 0.05 × 1000 × (28-15) / (24 × 160 × 0.95) = 9.95kW

Daily replenishment heating load Q h2 = P h2 × 24 = 9.95 × 24 = 238.68kwhr

(3) Water consumption of shower and daily heat load Q h3 : daily hot water volume 6750 liters / day (55 ℃); hourly maximum hourly water flow rate is 1/3 of daily hot water consumption W h = W / 3 = 6750/3 = 2250 liters / hour. Daily heat load Q h3 = W × (55 - 15) / (860 × 0.05) = 6750 × 40/817 = 330.48 kwhr

The daily heat load of the pool is ΣQ h = Q h1 + Q h2 + Q h3 = 1785.6 + 238.68 + 330.48 = 2354.76 kW.

3.2.3 host selection calculation

1) To meet the requirements of changing the water in winter, the number of primary engines and the number of units to be checked, and then checking whether the working hours are between 24 and 48 hours. And the average daily temperature in winter and the lowest cold water temperature to calculate

(1) primaries a company 300 heat pump hot water unit. The host at the temperature of 15.37 ℃, the output thermal power of 80.59kW, the input power of 25.07 kW.

(2) The number of hosts N = P 2h /80.59=150.44/80.59=1.8647

(3) Take the first 2 sets

(4) Working Hours of Main Engine H = (P 2h × 48) / (80.59 × 2) = (150.44 × 48) / (80.59 × 2) = 44.8 hours (within 48 hours)

2) Daily daily heat load, the host day working hours accounting

(1) Calculated in winter conditions: H 1 = ΣQ h /(80.59×2)=2354.76/(80.59×2)=14.61 hours.

3) extreme minimum temperature, the host 24 hours fully open, the required auxiliary electric heating calculation:

The local minimum temperature of 0.2 ℃, heat pump host output power of 47.4 kW, the input power of 19.58 kW.

The total heating capacity of the host 24 hours: 47.4 × 2 × 24 = 2275.20 kW

At extreme minimum temperatures, the day-to-day heat load also increases due to a drop in the water temperature (tap water temperature), Q h1 = 1785.6 kW

Q h2 = 300 × 0.05 × 1000 × (28-10) /860×0.95=330.48 kW

Q h3 = W × (55-10) /860×0.95=6750×45/817=371.78 kW

The total daily load is: 1785.6 + 330.48 + 371.78 = 2487.86 kW

Lack of electricity for the 2487.86-2275.20 = 212.66 degrees

The required auxiliary electric heating is 212.66 / 24 = 8.86 kW and the design is 10 kW.

3.2.4 Number of storage tank and volume calculation:

According to the requirements of the process, two water tanks should be used, one water tank has a circulation (middle) water tank and serves as a buffer tank for the water circulation hot water system in the heating pool. The other has the function of thermal storage water tank to meet the needs of peak water such as showers. In addition, its volume should meet the requirements of both to consider.

1) circulating hot water flow: hourly cooling water: 74.4 kW × 860 = 63980 kcal / hr, supposing the heating water is reduced from 55 ° C. to 50 ° C., the circulating heating water is required to be 63980 / (55-50) × 0.05 = 13470l /hr=13.47 m 3 / hr.

2) The buffer tank volume is taken as 30 minutes of flow, then V = 13.47 * 30/60 = 6.735 m 3 .

3) Shower peak water consumption: in each batch, the maximum water consumption is 2250 l.

4) the desired effective volume of the tank: 6.735 + 2.250 = 8.985 m 3

Design for 6 m 3 water tanks 2 for 12 m 3 total.

According to the above calculation, the equipment of the case is as follows:

HAM300 hot spring hot water unit 2 units

Auxiliary electric heater 10 kw 1 (placed in the water tank)

Water tank 6 m 3 2 units

3.3 program economy

If you can take advantage of hot and humid air indoor swimming pool heat pump heat pump unit. After the host evaporator absorbs heat and desiccates it, the dry and cold air coming out of the host directly into the swimming pool space or as a fresh air supplement for indoor pool air conditioners can greatly reduce unit power consumption and achieve the purpose of dehumidifying and dehumidifying for free . Host selection, the temperature can be calculated as 28 ℃. At this point, 300-type host output power of 108.2kw, input power of 27.98kw, daily heat load of 2446.52 kW. The working hours of 2 hosts are H 1 = 2446.52 / 108.2 × 2 = 11.31 hours. To outdoor air as a heat source and indoor air as a heat source of energy-saving comparison in Table 5 below

table 5

project

Outdoor air as a heat source

Indoor wet air as a heat source

surroundings

temperature

℃

Summer ℃

28

28

Spring and autumn ℃

twenty three

28

Winter ℃

15.37

28

Daily heat load with kW

summer

ΣQ h

2221.65

2221.65

Spring and autumn

ΣQ h

2288.2

2288.2

winter

ΣQ h

2354.76

2354.76

Host heating

Power and electric power

Rate kW

summer

108.20 / 27.98

108.20 / 27.98

(When the temperature is 28 ℃)

Spring and autumn

95.80 / 26.72

winter

80.59 / 25.07

Two hosts

Day working hours

H

summer

10.27

10.27

Spring and autumn

11.49

10.57

winter

14.61

10.88

power consumption

(degree)

summer

52873

52873

Spring and autumn

116767

108244

winter

65929

54796

Total annual electricity consumption (degrees)

235569

215913

Annual electricity savings (degrees)

19656

Annual electricity savings (0.89 yuan / kWh)

17493.84 yuan

Free cold capacity

619147.80kwhr

Annual total system heat

835060.8 kwhr

Energy efficiency throughout the year

3.5449

3.8676

From the above calculation, we can see that the utilization of the hot and humid air inside the swimming pool not only saves 19656 kWh of electricity but also provides cooling capacity of 610147.8 kW (equivalent to 53246 kcal / year) Energy-saving air-conditioning 20638 kWh, heat pump annual energy efficiency increased by 0.3227, COP increased by about 9.1%.

Swimming pool electricity situation

Single glazing

Double glazing

Small glass window

1

2

3

1

2

3

1

2

3

Fast water heater. Heated seats * , siding heating * , underfloor heating * , and heat in the bathroom

( 2 pool area)

1000

1500

2200

600

900

1800

200

400

1200

Small heat pump units, water circulation pumps, lighting and other power consumption

( 2 pool area)

800

900

900

800

900

900

800

900

900

Total indoor pool power consumption

( 2 pool area)

1800

2400

3100

1400

1800

2700

1000

1300

2100

project

Outdoor air as a heat source

Indoor wet air as a heat source

surroundings

temperature

℃

Summer ℃

28

28

Spring and autumn ℃

twenty three

28

Winter ℃

15.37

28

Daily heat load with kW

summer

ΣQ h

2221.65

2221.65

Spring and autumn

ΣQ h

2288.2

2288.2

winter

ΣQ h

2354.76

2354.76

Host heating

Power and electric power

Rate kW

summer

108.20 / 27.98

108.20 / 27.98

(When the temperature is 28 ℃)

Spring and autumn

95.80 / 26.72

winter

80.59 / 25.07

Two hosts

Day working hours

H

summer

10.27

10.27

Spring and autumn

11.49

10.57

winter

14.61

10.88

power consumption

(degree)

summer

52873

52873

Spring and autumn

116767

108244

winter

65929

54796

Total annual electricity consumption (degrees)

235569

215913

Annual electricity savings (degrees)

19656

Annual electricity savings (0.89 yuan / kWh)

17493.84 yuan

Free cold capacity

619147.80kwhr

Annual total system heat

835060.8 kwhr

Energy efficiency throughout the year

3.5449

3.8676

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