Community Research and Development Information Service - CORDIS

Periodic Report Summary 1 - EXP-HEAT (Energy recovery in new and retrofitted heat pumps using a dedicated expander concept)

Project Context and Objectives:
The main concept of the EXP-HEAT project is to replace the throttle or expansion valve used in common vapour-compression units with an expansion machine. Its purpose is to recover energy from the high-pressure liquid (condensed) refrigerant and provide it to the compressor, reducing its electricity consumption. The expansion machine can either be integrated in new heat pump design or retrofitted to existing units.

Project Results:
At the present phase of the project a dedicated liquid expander has been designed, manufactured and tested. Actually a hydraulic piston motor has been re-designed and a prototype has been manufactured to serve this purpose (Cover Photo). At first, the technology of hydraulic piston expander was selected over the reciprocating one and was then studied, starting from the boundary conditions determined by the heat pump thermodynamic cycle. Through a dedicated simulation model, the technical data of the heat pump units (capacity, temperatures, pressures, etc) have been defined. Then, appropriate tools have been developed to simulate the operation of the expander, and to estimate its performance. The tools have been used to suggest the main modifications on the expander. According to the design modifications carried out, the expander has been manufactured. A test-rig equipped with all necessary measurement instruments has been designed; it has been installed first in the FIR laboratory, in order to calibrate the measurement system and to test the expander with compressed air. Then, the test-rig has been moved to DORIN premises, where a high-pressure rig operating with R134a is available. At DORIN, various tests have been performed to assess the performance of the expander in various conditions. Tests and optimization are still on going on the expander; however, first tests have shown interesting performance of the expander. The results of the first set of tests have been shown to the partners in the technical meeting held in Florence at the end of October 2014 and will soon be presented to the scientific community through two international conferences. In the meantime, a semi-empirical model for the expander has been developed which is currently fed with the first experimental results and compared over its precision and accuracy with the initially developed simulation models and the actual measurements.
Figure 2 shows the manufactured expander mounted on the test-rig. The manufactured is made by two main parts: one (on the right, mainly in brown colour) that contains the nine axial pistons; the second one (on the left, main in silver colour) contains the distributor system. Figure 3 shows the rotating and stationary plates used for the suction and discharge of the fluid to/from the cylinder. The stationary (on the right)and the rotating plates (on the left) have been manufactured in base of the re-design of the original hydraulic motor. The rotation of the rotating plate determines the timing of suction and discharge phases for each cylinder

Potential Impact:
The overall objective of the project is to open new markets for the participating SMEs, and further develop new products and services, in order to magnify their business cycle. The outline of the project is carefully planned to deliver the required impact:
The heat pump market
An improved re-designed heat pump unit of higher efficiency offered at slightly higher cost will be introduced by EURE, while it is anticipated to have a very low pay-back-period, securing its cost effectiveness. On the other hand, the retrofit kit can be installed in a variety of heat pumps and boost their performance. This can be achieved with limited effort and cost, putting THERMO in a leading position.
Other potential markets
The same expander (perhaps modified) can be also integrated in refrigeration or air-conditioning units, enhancing their performance. Moreover, the 1-2 kW expander has the potential to be used for micro-scale applications like ORCs, where this technology has the potential to become competitive with micro-turbines, which typically require very high rotational speeds.

List of Websites:


Georgia Mertzelou, (Head of the Secretariat of the Research Committee)
Tel.: +30 2107721348
Fax: +30 2107724181
Record Number: 187449 / Last updated on: 2016-08-19