Height difference between energy storage tank and heat pump

Does a storage heat pump have a higher heating capacity?

The storage heat pump system shows an average 20 % higher heating capacity during system operation in Mode II (between 205 and 285 min). This is because the storage heat pump system uses the relatively warmer water from the lower tank region as the evaporator heat source, while the conventional system continues using ambient air as the heat source.

What is the performance of a storage heat pump system?

Performance of the storage heat pump system obtained for the operating conditions shown in Table 2 is compared to a conventional HPWH that uses a heat pump to heat water from 26 °C to 46 °C (t = 0 to 205 min) and then uses back-up electric elements to obtain the additional increase in water temperature from 46 °C to 58 °C (t > 205 min).

Do heat pumps have a storage tank?

Heat pumps have a significant and increasing share in the European heating market. In most applications heat pumps are operated with a storage tank, either for domestic hot water or for the space heating circuit.

How does a storage heat pump system differ from a conventional system?

This results in a higher lift in the evaporating pressure and consequently a higher refrigerant mass flow rate and heating capacity for the storage heat pump system when compared to the conventional system. The bulk average water temperature in upper and lower tank regions for the two systems is compared in Fig. 12 (b).

Why does a storage heat pump reach a higher bulk average water temperature?

The storage heat pump system can reach a higher bulk average water temperature in the upper tank region due to the higher heating capacity in Mode II when compared to the conventional system. Fig. 13 shows the heating performance factor (HPF) as a function of time for the storage heat pump and conventional heat pump systems.

How does a storage heat pump work?

The storage heat pump system operates in two modes to obtain a high temperature lift. The lower portion of the water tank is used as thermal energy storage element enabling the system to first pump heat from a low to an intermediate temperature before the heating energy is then lifted to a higher temperature in the second step.