Optimal design strategy of selection and combination to multi-air source heat pump units for central heating

Abstract

The air source heat pump (ASHP), as an energy-saving and environmentally friendly heating technology, has been widely used in central heating projects. The initial selection scheme of ASHP plays a crucial role in improving partial load performance, especially for fixed frequency ASHP units. To improve the performance of an ASHP scheme, where the scheme contains a number of ASHP units, the design and operation of several ASHP units in central heating systems were studied. Combined with field test results, the simulation calculation of different schemes was carried out and the optimal selection scheme which had both stability and high performance was obtained. By choosing units that have different nominal heating capacities, this can improve performance by up to 6% compared with the traditional scheme where all units have equal nominal heating capacity. By calculating performance under different building loads, it was concluded that the highest coefficient of performance (COP) can be achieved when the number of units is three and the nominal heating capacity ratio of the different units is 2:3:4. At the same time, a new concept was proposed to evaluate the overall operating load of the unit.