The heat pump is the device intended for transmission of energy from source to the consumer. Such pumps use renewable energy sources, for example, low-potential heat of soil, underground waters, air and other sources. The efficiency of use of the heat pump in many respects depends on whether its parameters are correctly calculated.
It is required to you
- - calculator;
- - basic data.
Instruction
1. Before starting calculation of key indicators of the heat pump, it is necessary to consider possible options of obtaining low-potential energy, for example, from soil. Heat energy can be received by laying of the metalplastic pipeline in trenches up to one and a half meters in depth or wells. At the same time removal of heat from each running meter of pipe depends on depth of laying of the pipeline, quality of soil, availability of underground waters and other indicators.
2. It is considered that the power of the energy emitted by each meter of horizontal collector is 20 watts. If to be more precisely, then heat conductivity of dry sand makes 10 W / (m*k), dry clay – 20 W / (m*k), damp clay – 25 W / (m*k), and clays with high content of water - 35 W / (m*k). When calculating the heat carrier temperature difference in direct and return lines of the pipeline is accepted equal 3 wasps.
3. Length of each trench has to be from 30 to 120 meters, and distance between pipes – 0.8 meters. As a rule, the heat carrier of primary contour – 25% solution of glycol. Its thermal capacity at zero temperature is equal 3.7 kJ / (kg*k).
4. If in heat pump system antifreeze is used, it is necessary to consider that pressure losses in the pipeline will be one and a half times more, than during water circulation. To calculate parameters of primary contour of the heat pump, it is necessary to define antifreeze consumption before. For this purpose substitute values in formula: Vs=Qo*3600 / (1.05*3.7*.t), where Qo – heat energy which is received from low-potential source, and.t – difference temperature equal to 3 OS.
5. The heat energy arriving from low-potential source pays off as difference between the ultimate power of the pump unit and power which is spent for freon heating. Then calculate length of pipes of the collector by formula: L = Qo/q, in which q – indicator of specific heat removal from one meter of pipe. After it count site length under collector: A = L*da, where da – pipe laying step.
6. In view of the fact that temperature of antifreeze fluctuates from-5 to +20os, in primary contour of the heat pump the expansion tank, and on return line – tank store has to be established. Its minimum volume is accepted at the rate of 10–20 liters on 1 kW of power of the pump unit.
7. Power of the heat pump is defined proceeding from its operating mode. At monovalent operating mode this device is used as the only generator of energy. The bivalent system of operation of the pump provides the additional electric heater (peak electric power in it case is 9.7 kW).