Heat pump hot water unit in swimming pool application (a)

1.1 pool heat loss

Swimming pool outdoor open-air swimming pool (field) and the indoor heated swimming pool (Museum) two categories. From the nature of the use of swimming pool, swimming pool, training pool, diving pool, children play pool, etc .; from the nature of the business, there are public swimming pool, commercial hotel swimming pool, there are private villas and other residential swimming pool. However, no matter what kind of swimming pool, there is a requirement to maintain the constant temperature of the water, and the temperature of the water varies with the nature of the use. Swimming pool heat loss in the following areas:

1) Pool Water is constantly losing heat due to water surface evaporation, water surface conduction, pool bottom and pool wall conduction.

2) As people swim in the swimming pool, a part of the water will be lost and must be continuously replenished. However, the supplementary water needs heating and needs to be supplemented with some heat.

3) In addition, the entire pool of equipment and piping is also constantly emitting heat to the surrounding environment.

Some of these losses of heat, we need to continue to supplement, in order to maintain a certain temperature of water. These heat losses, combined with the heat loads of swimming pools and showers, can be referred to as recurrent heat loads.

In addition, there is also a one-time water temperature pool replacement of all new requirements. In order to clean, disinfection requirements, in a certain period of time, all the water required to empty the pool, re-enter the warm water. If the supplementary water is cold water (water temperature at 5-15 ℃), then the heat required to heat the entire pool of water is a one-time impact load.

1.2 pool water temperature

General indoor swimming pool water temperature is 24-29 ℃, outdoor is 22-30 ℃. If the indoor swimming pool has a perfect air-conditioning heating facilities, can be taken as 25 ℃; if the temperature is low, can be taken as 27 ℃. The heat loss is related to the temperature of the water in the pool and also to the temperature of the surrounding environment (eg air). General indoor temperature is higher than the water temperature of 1-2 ℃. Foreign information shows that: the best indoor swimming pool environmental parameters:

Air temperature 26-30 ℃

Pool water temperature 25-28 ℃

Ground temperature 30-32 ℃

Wind speed 0.05-0.1m / s

Relative humidity 50-60%

1.3 indoor swimming pool relative humidity

To maintain a certain indoor swimming pool relative humidity is necessary. When the outdoor temperature is -10 ℃ and the indoor air relative humidity is 50-60% and the heat transfer coefficient of the double glazing is 2.9W / m 2 , the glass window will still be wet and dew; even if the outdoor temperature is -1 ℃, the room is 28 ℃, it will dew. Therefore, swimming pool venues must be dehumidified.

1.4 pool heat load calculation

The former mentions that for the heat load of the swimming pool, there are:

a. water surface evaporation heat;

b. water surface conduction heat;

c. Pool bottom, pool wall conduction heat;

d. equipment and pipe cooling;

e. water heating;

f. swimming pool shower with heat;

Due to evaporative cooling, conductive heat dissipation calculation is very complicated, and must have the swimming pool structure of the detailed dimensions, weather, soil and other information, in order to estimate the convenience of a, b, c, d four, can be combined into one, namely: By the surface area of ​​the swimming pool m 2 average heat loss. See Table 1

The values ​​in the table are calculated according to the following conditions: water temperature 27 ℃, air relative humidity 50%, wind speed: indoor 0.5m / s; outdoor 2m / s

Foreign information, for the heat loss of outdoor swimming pool, you can also estimate the following data; at a water temperature of 23 ℃, the average temperature of 10-12 ℃,

Convection heat loss 70? 95W /?

Radiant heat loss 60-80 W /? (At night)

Heat radiation ≤ 180 W /? [Day]

Evaporative heat loss 350-700 W /?

Replenishment of water when the heat 400-600 W /?

For replenishment heat loss, you can press the amount of water and make up the temperature difference calculated. Table 2 shows the percentage of swimming pool water volume per day.

Proposed in the scheme design: open-air pool to take 10% = B1; indoor pool to take 5% = B2. Due to replenishment need to heat the hour power can be calculated as follows

P = [(V × B × 1000/24) × (t 2 -t 1 ) / 860] kW, (1-1)

Where: P-replenishment heating power, kW;

V-pool volume, m 3 ;

B - Replenishment volume percentage,%;

t 1 - recharge the initial temperature, ℃;

t 2 - water temperature, ℃.

As for the swimming pool used shower, washing and other hot water consumption calculation and heating load required, according to conventional calculations.

For a one-time impact load, according to the water change and water temperature rise to calculate the total heat power and hours with the heat power (the heating power required for the machine). Total thermal power Q Zh

Q Zh = 1.15 × V × (t 2 -t 1 ) × 1000/860 kW, (1-2)

Hour thermal power P h = Q Zh / T kW, (1-3)

Where: V - the total volume of swimming pool, m 3 ;

t 2 - the required temperature of water, ℃;

t 1 - cold water temperature, ° C;

T-water cycle, h;

1.15 - Consider the added value of heat loss during the water change cycle.

The general initial filling or changing the water cycle T is 24-48h meter. In other words, it is required to complete the entire pool of water change within 24-48h. As for how often the water should be changed according to the user's requirements for the use of the swimming pool and operating conditions. As the water is constantly circulating filtration and disinfection, the time interval is relatively long, can be a month, six months, or even a year, for the nature of the pool pool, it is possible to change the water once a day. For venues with several swimming pools, the water change time can be staggered when calculating the load. When selecting the host, according to a one-time load of the maximum volume of the pool to calculate, you can also use the length of the water change cycle to adjust. Table 3 shows the number of cycles and cycles for different types of swimming pools.

The general practice of swimming pool heating and rehydration heating can be seen in Figure 1.