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Differential Aggregate

 APPLICATION Projected parameters and results: Power generation from hot gas Between 70-150 oC the efficiency= 38% Between 150-400 oC the efficiency= 60% Between 400-800 oC the efficiency= 70% Natural gas liquefaction (LNG) Cooled to -161 oC with 5 bar compression pressure Air liquefaction Cooled to -195 oC with 5 bar compression pressure Power generation from hot water Between 60-150 oC the efficiency= 15-30% Cooler or chiller (without defrost problem) Between -40 – 0 oC the COP is greater than 8 Air conditioner (without defrost problem) Ambient temperature: -25 -to 50 oC Controlled temperature: 15-25 oC COP greater than 8 Heat pump for heating (without defrost problem) Ambient temperature: -35 oC -to 10 oC increased temperature: 65 oC COP greater than 8 Vapour condensation from air Ambient temperature: 0 – 50 oC COP = 8 Energy generation from (industrial) waste heat With 50- 80 oC temperature difference: efficiency is between 15-30 % With 100- 300 oC temperature difference: efficiency is between 35-55 % Engine for vehicle Between 100-150 oC the efficiency= 40% Between 150-400 oC the efficiency= 55% Between 400-800 oC the efficiency= 70%

’Efficiency’ means the projected thermal efficiency of the energy conversion.

Inverse Heat Pump

Basics:

Most of the heat pumps have evaporating – condensing working fluid. They use electric motors to drive the heat pump's compressors. The heat pumps usually have Carnot, Lorentzen or Brayton cycle..

The heat pump collects the heat energy from the cold side and transports it to the hot side. The cooling material has lower temperature, than the the cold side, so the heat energy moves toward the colder place.

The Coefficient of the Performance shows the rate of the moved heat energy and the power needed for the heat transport. Another important parameter is the difference of the lower and higher temperature of the heat pump. The larger the difference the smaller the COP is. This is a huge disadvantage for the existing heat pumps.

Theoretically the COP of the regular heat pumps can reach the value of 4,0 in case of a temperature difference -20oC and 65 oC, but the energy transport is too small. In practice most of heat pumps used for heating can work above -5 oC temperature, but under this temperature they work as an electrical heating equipment.

For cooling purposes the result is similar, but in that case the COP is less by 1,0 compared to the COP of the heating application.

Inverse technology:

The basic inverse heat pump consists of compressor and expander units, and at least 2 heat exchangers. See the Fig. 1. Fig. 1.

The process:

The air from the cold side enters to the heat exchanger No 25 at point 1. It has 1 bar pressure and cold ambient temperature. Than it starts to get warmer in the heat exchanger No 25. The warm air enters the compressor at point 2 and its pressure and temperature are increased until point 3 by the compression work.
After point 3 the air drops some heat energy by the heat exchanger No 24 toward the warm area. At point 4 the relatively warm air enters the heat exchanger No 25 and cools down to the cold ambient temperature, while it warms up the intaked cold ambient air.
Expander No 23 expands the high pressure air on cold ambient temperature to the ambient pressure, while the air is getting colder. The cooled air now on smaller volume is pushed to the cold ambient area, where it can warm up and get heat energy from the cold ambient air.

Rotating piston units are used for compressor and expander, that you can see on the Fig. 2 and 3.
The key element of the inverse technology is, that the working fluid air is heated up before the compression. This compression work is higher, than work of the colder air compression, but in the end the compression energy is much smaller than the regular Carnot work needs. We can use larger heat difference between the cold and hot side by preheating of the air.
The entered and exhausted cold air has different volume, so the volumetric work gives positive result against the 1 bar ambient atmosphere. Fig. 2.

The “heat carousel” generates heat energy transport by the heat exchanger, by the air flow and by the volumetric work difference. These 3 energy transports result in the high COP for inverse heat pump.

The air flow moves Q=m*Cv*dt heat energy, the heat exchanger transports Q=m*Cp*dt heat energy and the volumetric work generates L=p*V work.

The inverse heat pump increases the difference in the cold and hot temperatures by the heat energy and volumetric work transport with no additional need for a compressor drive. Most of this energy is cowered by the compressor work in a Carnot machine.

Model calculation:

The calculation is based on the Gas Law:
(p1 * V1 / T1 = p2 * V2 / T2)

We use the numeric integral of the adiabatic compression and expansion to calculate the volumetric work of the processes.
L = p2 * v2 - Wcomp - p3 * v3 + p5 * v5 + Wexp - p6 * v6

Where the Wcomp is the work need of the adiabatic compression and the Wexp is the work of the adiabatic expansion.
The p*v is the volumetric work of the air transport.
There is no closed thermodynamic cycle in this system, so the energy balance was calculated process by process for all 3 energy forms. Fig. 3.

Initial values:

Point 1: working fluid is ambient air: p1 = 1 bar, t1 = -5 oC

Results:

Point 2: working fluid is ambient air: p2 = 1,00 bar, t2 =   67 oC, v2 = 1,000
Point 3: working fluid is ambient air: p3 = 1,20 bar, t3 =   85 oC, v3 = 0,878
Point 4: working fluid is ambient air: p4 = 1,20 bar, t4 =   67 oC
Point 5: working fluid is ambient air: p5 = 1,20 bar, t5 =   -5 oC, v5 = 0,657
Point 6: working fluid is ambient air: p6 = 1,00 bar, t6 = -19 oC, v6 = 0,748

Developing directions:

The system is opened in our example. If we close the cold side of the inverse heat pump with a heat exchanger, we can use higher pressure (10-50 bar) inside and different working fluid. In this case the mass flow is higher and the rated power is higher too.

The inverse heat pump is usable for cooling purpose too. The COP is lower by 1.0, than the heating COP was, bat the cooling COP is higher than the Carnot COP would be.

Advantages of the inverse heat pump:

• The inverse pump can reach better performance than the present heat pumps have

• The heat difference can be larger than some 100 oC with COP more than 3.0

• The inverse cooler's COP is relatively stable even in case of wide range of the ambient temperature

• The COP is more than 3,0 in -60oC - 0oC lower temperature range

• The working fluid is the ambient air, which is cheap and environmentally friendly

• There is no need for defrost at the cold side

• The vapour content of the ambient air increases the power

• There isn't vapour condensation inside of the inverse heat pump