Prediction of Stirling-Cycle-Based Heat Pump Performance and Environmental Footprint with Exergy Analysis and LCA

The use of Stirling-cycle-based heat pumps in high-temperature applications and waste heat recovery at an industrial scale is of increasing interest due to the promising role in producing thermal energy with zero CO2 emissions. This paper analyzes one such technology as developed by Olvondo Technology and installed at the pharmaceutical company AstraZeneca in Sweden. In this application, the heat pump used roughly equal amounts of waste heat and electricity and generated 500 kW of steam at 10 bar. To develop and widen the use of a high-performance high-temperature heat pump that is both economically and environmentally viable and attractive, various analysis tools such as exergy analysis and life cycle assessment (LCA) can be combined. The total cumulative exergy loss (TCExL) method used in this study determines total exergy losses caused throughout the life cycle of the heat pump. Moreover, an LCA study using SimaPro was conducted, which provides insight into the different emissions and the overall environmental footprint resulting from the construction, operation (for example, 1, 8, and 15 years), and decommissioning phases of the heat pump. The combined results were compared with those of a fossil fuel oil boiler (OB), a bio-oil boiler (BOB), a natural gas-fired boiler (NGB), and a biogas boiler (BGB).

Investigating student understanding of a heat engine: a case study of a Stirling engine

We report on the study of student difficulties regarding a heat engine in the context of a Stirling cycle by the method of measurement. An in-class test about a Stirling engine with a regenerator was taken by three classes, and the students were asked to perform one of the most basic activities—calculate the efficiency of the heat engine. Our data indicate that quite a few students have not developed a robust conceptual understanding of basic engineering knowledge of the heat engine. Notably, the error ratio of the class given a simple tutorial of engineering knowledge is smaller than those of the other two classes by more than 20%. In addition, both the written answers and post-test interviews show that most of the students cannot associate Carnot’s theorem with a Stirling cycle. Our results suggest that both scientific and engineering knowledge are important and should be included in instructional approaches, especially in the thermodynamics course taught in the countries and regions with a tradition of not paying much attention to experimental education or engineering training.

A Potential Method to Predict Performance of Positive Stirling Cycles Based on Reverse Ones

There are two kinds of working mechanisms for the Stirling cycle, i.e., the positive and the reverse cycles, and a Stirling engine (SE) can be operated as a Stirling refrigerator (SR). This indicates that a probable practical method for evaluating the performance of a Stirling engine is to run it as a refrigerator, which is much easier to operate. For this purpose, an improved Simple model for both the positive and the reverse Stirling cycles, considering the various loss mechanisms and actual operating conditions, is proposed and verified by a self-designed Stirling engine. As to the positive cycle with helium and nitrogen at 2.8 MPa, the model errors range from 5.4–11.3% for the indicated power, and 1–10.2% for the cycle efficiency. As to the reverse cycle with helium and nitrogen, the errors of the predicted input power range from 7.9–15.3% and from 2.5–10.9%, respectively. The experimental cooling temperatures can reach −92.2 and −53.6 °C, respectively, for the reverse cycle with the helium and nitrogen at 2.8 MPa. This Stirling-cycle analysis model shows a good adaptability for both the positive and the reverse cycles. In addition, the p-V maps of the positive and reverse cycles are compared in terms of “pressure ratio” and “curve shape”. The pressure ratio of the reverse cycle is significantly higher than that of the positive one at the same mean pressure. A method is proposed to predict the indicated work of the positive Stirling cycles using the reverse ones. A mathematical model to predict the indicated power of the positive Stirling cycles based on the reverse ones is proposed: Wheat2−Wcool1=A·(Tge2−Tgc2Tgc1−Tge1)B. The most critical issue with this method is to establish an associated model of the temperatures of the expansion and the compression space. This model shows a good adaptability for both the positive and the reverse cycles and can provide detailed information for deep discussion between the positive and the reverse cycles.

Non-commutative space engine: A boost to thermodynamic processes

We introduce quantum heat engines that perform quantum Otto cycle and the quantum Stirling cycle by using a coupled pair of harmonic oscillator as its working substance. In the quantum regime, different working medium is considered for the analysis of the engine models to boost the efficiency of the cycles. In this work, we present Otto and Stirling cycle in the quantum realm where the phase space is non-commutative in nature. By using the notion of quantum thermodynamics, we develop the thermodynamic variables in non-commutative phase space. We encounter a catalytic effect (boost) on the efficiency of the engine in non-commutative space (i.e. we encounter that the Stirling cycle reaches near to the efficiency of the ideal cycle) when compared with the commutative space. Moreover, we obtained a notion that the working medium is much more effective for the analysis of the Stirling cycle than that of the Otto cycle.

Analisa Isolasi Pipa Generator Mesin Stirling Tipe Alpha Sudut Fasa 180°

This research is a development of previous research, where in the previous research, a design innovation was carried out on an alpha-type stirling engine by making the phase angle to 180o, with the aim of reducing the effect when the cold cylinder is compressed, because the phase angle currently used is (90o) with disadvantages, namely the cold cylinder is perpendicular to the top, so that the compression process against gravity. But in previous studies, the generator pipe was too long, causing a lot of energy or heat loss (heat loss) so that the compression speed was small. So that in the research, innovated and analyzed the pipe insulation of alpha-type stirling engine generators, alpha-type stirling engines, 180o phase angle. The research method used is to use the thermodynamic approach with Schmidt theory and the theory of the ideal cycle stirling engine. while the simulation is done using the Ideal Stirling Cycle Calculator. Results investigated shows that providing insulation on the generator pipes of an alpha-type stirling engine for an alpha-type stirling engine with a 180o phase angle is proven to reduce a lot of energy or heat loss (heat loss) due to too long generator pipes, with a heat loss value ratio of 226.66 W for the pipe. generator that uses insulation whose value is smaller than the value of the heat loss when the generator pipe without using isocation is 1,584.12 W.