Figure 5 - available via license: Creative Commons Attribution 4.0 International
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Temperature map of the efficiency η of the heat engine in terms of the interaction potentials V h and V c between the Double Quantum Dots (DQDs) for fixed parameters: ∆ h 1 = ∆ c 1 = 10, ∆ h 2 = ∆ c 2 = 3, kT h = 2, kT c = 1. The green region for V h > V c represents the negative values of the efficiency (η < 0) and the grey region is a region where the efficiency surpass the Carnot efficiency (η > η c = 0.5).
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This paper presents a conceptual design for quantum heat machines using a pair of coupled double quantum dots (DQDs), each DQD with an excess electron to interact, as an working substance. We define a compression ratio as the ratio between the Coulomb potentials which describes the interaction between the electrons during the isochoric processes of...
Contexts in source publication
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... start by plotting the work done and the efficiency of the heat engine in terms of the interaction potentials V h and V c in the Fig. 4 and Fig. 5, respectively, where we have set 1 ∆ h 1 = ∆ c 1 = 10, ∆ h 2 = ∆ c 2 = 3 and kT h = 2, kT c = 1, where from this point now we restrict ourselves to the case where the tunneling parameters ∆ 1 and ∆ 2 are the same for the whole cycle and we will no longer worry about the upper index. It is clear from the Fig. 4 that we need V c > V h to ...
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... is in contact with the cold reservoir and they are expanded when the system is in contact with the hot reservoir [38]. Note that we can not increase the potential V c indefinitely since the positive work condition is lost. There is a limited region for V c > V h between the blue curves, as illustrated. Notice that, just like in the work plot, the Fig. 5 tells us that we need V c > V h in order to achieve a positive efficiency, η > 0. Also, there is an uniform increase on the efficiency given by the temperature map (where the more reddish regions corresponds to higher values of the efficiency and the more bluish regions to the lower ones) which is followed by a tiny region where the ...
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... /V h . In the Fig. 6 the heat exchanged Q h (Q c ) with the hot (cold) reservoir in terms of the compression ratio r is shown. It is observed that, as we increase the value of r, it comes to a point where there is no heat transfer even when the system is in contact with the hot and the cold reservoir (this point generates the discontinuity in the Fig. 5). Furthermore, after this point, the signs of the heats exchanged are inverted and the system starts to withdraw heat from the cold reservoir and transfer heat into the hot reservoir. In other words, the system starts behaving as a refrigerator at cost of some ...
