1 Project Overview

The research and development base is located in Tongzhou District, Beijing, spanning 580 acres of land, with approximately 150 acres dedicated to waste pit ponds. The total construction area is 95,000 square meters, with primary functions including scientific research, development, warehousing, offices, and experimental housing. The approximate distribution includes: R&D space at 100,000 square meters, experimental residential buildings at 3,000 square meters, public facilities at 74,000 square meters, and municipal areas at 22,000 square meters. Given the site's conditions and environmental requirements, a surface water source heat pump system has been proposed for heating and cooling.

2 Feasibility of Using Surface Water Source Heat Pump System

A surface water source heat pump system uses surface water as a thermal resource for heating and cooling. It is known for its energy efficiency and environmental benefits, making it widely adopted both domestically and internationally. However, surface water often contains impurities such as sediment and algae, and due to its exposure to air, it has high oxygen content and can be corrosive. Direct use of surface water in heat pump units may lead to reduced unit lifespan, fouling, and performance issues. Therefore, it is recommended to separate the surface water from the building’s internal circulation using a heat exchanger. This approach allows for efficient heat transfer with minimal temperature difference, protecting the expensive heat pump units and enabling potential heat recovery between buildings. In cases where surface water temperature or flow does not meet requirements, auxiliary equipment like boilers in winter or cooling towers in summer can be used to supplement the system.

3 Cooling and Heating Load Estimation and Water Flow Feasibility

According to local climatic data, the average summer surface water temperature in Beijing ranges from 25-27°C. With a 5°C temperature difference in the heat exchanger, the inlet temperature for the heat pump unit will not exceed 32°C. During summer, the heat pump unit’s outlet temperature should remain below 37°C, ensuring normal refrigeration operation. In winter, the surface water temperature is typically around 4°C, and with a 2°C temperature difference, the inlet temperature for the heat pump unit would not exceed 2°C. To prevent freezing, antifreeze must be added to the circulating water, resulting in a COP value of 2–3. If the surface water temperature drops too low, auxiliary heat sources like gas boilers may be required to maintain efficiency.

4 Environmental Impact of Water Source Heat Pump Systems

The surface water source heat pump system operates by extracting and converting heat from surface water without chemical treatment. Only physical treatments like filtration and sedimentation are applied, ensuring that the composition of the water remains unchanged. As long as the system is properly designed and operated, it will not cause pollution to the local water bodies. The system is environmentally friendly and has minimal negative impact when functioning under normal conditions.

5 Technical and Economic Analysis

In terms of cost, the surface water source heat pump system eliminates the need for cooling towers during summer, reducing initial investment. While the operating costs may not show significant savings compared to traditional systems, the system’s efficiency and environmental benefits make it a favorable option. For winter heating, a comparison was made between a gas boiler + radiator system and a surface water source heat pump + fan coil system. The calculated operating cost for the heat pump system was about 22.1 yuan per square meter per heating season, which is lower than the 35 yuan per square meter for the gas boiler system. This results in annual savings of approximately 1.88 million yuan.

6 Conclusion and Recommendations

6.1 The surface water source heat pump system is feasible under current conditions, with only physical treatment required. 6.2 The system is environmentally safe if properly designed and operated. 6.3 In extreme cold conditions, auxiliary heat sources like gas boilers should be considered to ensure heating efficiency. 6.4 The operating cost of the surface water source heat pump system is significantly lower than that of a gas boiler system, offering substantial economic benefits.

References

Xu Wei, etc. Ground Source Heat Pump Engineering Technical Guide. Beijing: China Building Industry Press, 2001

Lu Yaqing Practical Handbook for Design of Heating and Air-conditioning. Beijing: China Building Industry Press, 1994