Alison Subiantoro

Exergy Analysis of the Revolving Vane Compressed Air Engine

Exergy analysis was applied to a revolving vane compressed air engine. The engine had a swept volume of 30 cm3. At the benchmark conditions, the suction pressure was 8 bar, the discharge pressure was 1 bar, and the operating speed was 3,000 rev·min−1. It was found that the engine had a second-law efficiency of 29.6% at the benchmark conditions. The contributors of exergy loss were friction (49%), throttling (38%), heat transfer (12%), and fluid mixing (1%). A parametric study was also conducted. The parameters to be examined were suction reservoir pressure (4 to 12 bar), operating speed (2,400 to 3,600 rev·min−1), and rotational cylinder inertia (0.94 to 2.81 g·mm2). The study found that a higher suction reservoir pressure initially increased the second-law efficiency but then plateaued at about 30%. With a higher operating speed and a higher cylinder inertia, second-law efficiency decreased. As compared to suction pressure and operating speed, cylinder inertia is the most practical and significant to be modified.

Study of torque matching of revolving vane compressor and expander

An investigation was carried out to find the most optimum configuration, particularly the torque matching characteristics, of an integrated Revolving Vane compressor- expander. To carry out the study, a mathematical model of the integrated compressor-expander was developed. An open cycle air refrigeration system was adopted. The controlled parameter was the angle shift between the compressor and the expander. The observed parameters were the peak torque requirement and the bearing load. The results show that when properly matched, the peak torque can be reduced by more than 65% while the bearing loads can be reduced by up to 25%, depending on operating conditions. Unfortunately, the optimum angle shifts for peak torque do not always coincide with those for bearing load. When the pressure and inertial components of the torques are comparable or when the inertial component is dominant, the optimum angle shifts for peak torque and bearing load are around 180° and 330°, respectively. When the pressure component is dominant, the optimum angle shift for peak torque is equal to the angle difference between the pressure peak torques of the compressor and the expander while for bearing load is around 150°.

A comprehensive simulation model of the dynamics of the revolving vane machine

A new and comprehensive mathematical model to simulate the revolving vane (RV) machine has been developed. The model allows the dynamics of the components to be fully dictated by forces and torques interactions, instead of restriction provided by their geometries alone. In general, the new model produces very similar kinematics predictions with that from the old model which is geometrically dictated. However, the new model is able to show some features which are previously not observable. These include the intermittent contact between the vane and the slot and the effects of the collisions between the vane and the slot.

Design limitations and flexibilities of the revolving vane compressor

The Revolving Vane (RV) compressor was invented in the year 2006. Due to its rotating cylinder mechanism, the mechanical efficiency of the mechanism is significantly higher when compared to its predecessors. In this paper, the practical and theoretical design limitations of the mechanism are discussed. These include the allowable maximum eccentricity, the vane slot geometry and the sizes of the compressor components. Proposed methods to overcome some of the limitations are then presented. The results indicate that the RV compressor has the potentials to be used even for compressor applications with space limitations.

Feasibility analysis of the hybrid dehumidifier–air conditioner technology for small-scale household applications in the tropics

Household air conditioners (ACs) with cooling capacities of less than 6 kW are popular in the tropics but are highly energy intensive because of the humid ambient condition. The hybrid dehumidifier–AC concept was studied here to improve the energy efficiency of such systems. Feasibility of the concept was investigated by looking at the design complexity, expected performance, and economic aspects. From the design analysis, it was concluded that small desiccant wheels are most practical for portable and window ACs, while no dehumidification concept was found ideal for split-type room ACs. Performance of the system was benchmarked with data from a 6.4 m2 room under tropical ambient conditions with air change rates of 1–4 changes per hour. It was found that an average load reduction of up to 8.1% was obtainable. The corresponding potential power saving was 9.4%. The performance data were then used for the economic analysis. It was found that the hybrid system is financially attractive mostly when cooling capacity, usage rate, and electricity price are high. Furthermore, the system should have a cooling capacity of at least 4 kW and 4 air changes per hour to be financially justifiable, particularly in places with low electricity prices.