Optimizing Water Heating Heat Pump Configuration for Schools: A Comprehensive Guide
Heat pump hot water units operate on the reverse Carnot cycle principle. The compressor’s movement causes the working fluid to change phases. Through this repeated phase – change cycle, heat is absorbed from external sources like air or water and transferred to cold water. As a result, the cold water is heated gradually and then distributed to users via the water circulation system. WHALE heat pump water heaters have found extensive applications in various settings, including hotels, factories, schools, hospitals, entertainment venues, and villas. In this article, we’ll delve into the process of choosing a suitable heat pump water heating system for schools.
Determining System Requirements: Maximum Daily Water Consumption and Water Tank Selection
1. Application Scope
- Schools typically require hot water for student showers, toilet facilities, dishwashing in the cafeteria, and kitchen operations. However, specific needs can vary significantly from one educational institution to another.
2. Calculating Water Requirements
- Student Shower Hot Water: On average, a consumption rate of 35L per student per day is considered, assuming all students use hot water simultaneously.
- Bathroom Sink Hot Water: Approximately 5L per person per day is allocated for this use.
- Dishwashing and Kitchen Hot Water: Calculated at 10L per person per day, based on two meals served daily.
Note: The hot water design is focused on essential needs such as bathing, face – washing, dishwashing, and kitchen vegetable – washing. Hot water for tasks like clothes – washing or mop – washing is not included. Schools should actively promote water conservation among students to ensure the efficient use of these precious resources.
Real – World Examples: School Heat Pump Installations
Xinzhan Town Central School in Southwest China
Water Tank Calculation
- School Background: This school has 922 students in total, with 144 living in dormitories. It requires sanitary hot water for student showers, face – washing, cafeteria dishwashing, and kitchen vegetable – washing. Considering future planning, development, and system standardization, meal – related hot water is projected for 1000 people, while shower and face – washing hot water is estimated for 200 people. The following table details the water consumption:
Hot Water Demand Occasion Users (person) Consumption(L) Total (T) Remark Canteen Sanitary Hot Water 1000 10 10 Fixed Amount Tap Hot water of Student Dormitory 200 5 1 Fixed Amount Student Shower Hot Water 200 35 7 Fixed Amount Total 18 Tank selection 20 - Tank Selection: Based on the calculated water demand, a water tank with a capacity of 20T is selected to ensure an adequate supply.
Heat Pump Selections
- Project Water Demand: The project requires up to 20 metric tons of domestic sanitary hot water. In winter, the lowest ambient temperature is 5°C, and the tap water temperature is around 10°C.
- Heat Calculation:
- To heat 20 metric tons of tap water from 10°C to 55°C, we use the formula:
- Q = CM△T. Here, Q = 1.1631(ton)(55 – 10)=52KWH for 1 ton of water
- For 20T of water, Q = 20*52 = 1040KWH.
- Heat Pump Capacity Adjustment: Air source heat pumps have a characteristic where the lower the outdoor temperature, the lower the heat output. When selecting a heat pump, its heat output must be adjusted according to different ambient temperatures. For example, when the ambient temperature is low, the capacity decreases. A single unit of WHALE PASHW100S-XI has a heating capacity of 12KW, and two units of PASHW100S-XI have a combined heating capacity of 24KW.
- Working Time Calculation: The required working time N = 1040/60 = 17h.
- Final Heat Pump Selection: Based on these calculations, the design incorporates one unit of PASHW100S-XI and two units of PASHW100S-XI to meet the school’s hot water needs efficiently.
