Magnetic Development, Inc. had developed the geothermal heat pump model with two-step compression First, the mechanical compressor compresses the vapor to approximately 50-60% of the final pressure and then additional compression is provided in an ejector using internal potential energy of the working fluid. Therefore, the amount of mechanical energy required by a compressor is reduced and the efficiency is increased by up to 40%.
The principle of our new cycle is shown in Figure 3. The system includes the main piping circuit (1) and (7) containing the evaporator (2), a compressor (3), an ejector device (4), a condenser (5), a separator tank (6), and an expansion valve (8). The circulation of a liquid phase for a working medium is provided by the additional liquid line (9), and a pump (10). The evaporator (2) absorbs the heat from source (11), while the condenser (5) is connected to the heat sink—high temperature heat receiver (12).
Schematics of geothermal heat pump with a condensing ejector
as a second-stage compressor
The theoretical energy savings for our system is established by analyzing the thermodynamic cycles for the new system vs. traditional single-stage compression cycle. Both cycles are presented below:
Comparison of p-h diagrams of the new refrigeration cycle with
a two-phase ejector, Cycle 1 (points: 1-2-3-4-5-6-1 and 6-7-8-4)
and the traditional cycle Cycle 2 (points: 1-2-3'-6-1).
Laboratory Model of 3.5 Ton Geothermal Heat Pump
with Condensing Ejector
Novelty of the Magnetic Development, Inc. Cycle:
Our new thermodynamic cycle is characterized by the location of the ejector device after the compressor discharge in order to increase the final cycle pressure (pressure at the inlet to the condenser), while all to-date designs used ejectors for increasing the suction pressure of the compressor,
Our ejector is working on the principle of critical (choked) flow of two-phase (liquid and vapor) mixture. Therefore the velocity in the mixing chamber exceeds the sonic velocity. We are using previous discoveries indicating that the sonic speed in two-phase mixture is much lower than that in any of its components. The originality of our approach lies in the fact that we are achieving M>1 (Mach number) not by increasing the velocity of flow but rather by slowing down the speed of sound by adjusting the composition of the mixture (instead of increasing the numerator, we reduce the denominator in the Mach number instead).
All previous designs of the ejector relied on the increase of the pressure in the mixing chamber by the process of equalizing the velocities of both motive and suction streams. Consequently, the value of outlet pressure was intermediate between the pressures of motive and suction streams. Our design, by utilizing the properties of critical flow, can produce the outlet pressure much higher than the pressure of any of the stream components. This is achieved by the creation of a “condensation shock”, previously acknowledged by few researchers, but never used in practice with refrigerant as a working medium.
We offer complete systems and installations
for geothermal heating and cooling:
- Commercial and Residential
- Open Loop or Ground Water Heat Pump
- Closed Loop (Ground Coupled Heat Pump) Horizontal
- Design and field supervision provided
by licensed Professional Engineers.