Analysis of the Air-Reversed Brayton Heat Pump with Different Layouts of Turbochargers for Space Heating

Abstract

The air-reversed Brayton cycle produces charming, environmentally friendly effects by using air as its refrigerant and has potential energy efficiency in applications related to space heating and building heating. However, there exist several types of cycle that need to be discussed. In this paper, six types of air-reversed Brayton heat pump with a turbocharger, applicable under different heating conditions, are developed. The expressions of the heating coefficient of performance (COP) and the corresponding turbine pressure ratio are derived based on thermodynamic analysis. By using these expressions, the effects of turbine pressure ratio on the COP under different working conditions are theoretically analyzed, and the optimal COPs of different cycles under specific working conditions are determined. It is observed that Cycles A and C have the highest heating COPs, and there is an optimal pressure ratio for each cycle. The corresponding pressure ratio of the optimal COP is different, concentrated in the range of 1.5–1.9. When the pressure ratio reaches the optimal value, increasing the pressure ratio does not significantly improve the heating COP. Take Cycle F as an example: the maximum error between the calculated results and experimental observation is lower than 5.6%. These results will enable further study of the air-reversed Brayton heat pump with a turbocharger from a different perspective.

Thermal Performance Design and Analysis of Reversed Brayton Cycle Heat Pumps for High-Temperature Heat Supply

“…Zühlsdorf et al [14] proposed MVR and RB systems, conducting an economic evaluation under operating conditions capable of delivering output temperatures above 280 • C, which verified the feasibility under given conditions. Huang et al [15] constructed a two-stage CO 2 RB system incorporating injection and an internal heat exchanger, performing simulation analysis according to the design parameters and an economic evaluation at an output temperature level of approximately 150 • C. Wang et al [16] modeled various RB systems with different placements of a turbocharger and an additional compressor, analyzing the impact of the pressure ratios on performance and examining the feasibility of supplying heat at space heating levels. White [17] identified the factors affecting the irreversibility of a heat pump for heating purposes at 65 • C in a thermodynamic analysis, highlighting the need for the pressure losses and component efficiency to be at reversible cycle levels under low-temperature conditions.…”

Four-Objective Optimization of an Irreversible Magnetohydrodynamic Cycle

“…Finite time thermodynamic (FTT) theory has been widely used in various heat engine cycles and has made great progress [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. In addition to analyzing the power output ( ) and efficiency ( ) performance of common engines, FTT has also been applied to heat pumps [ 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ], refrigerators [ 47 , 48 , 49 , 50 , …”