Influence of the position of recessed outdoor units and louvre blade angle on the performance of split air conditioners

In residential air conditioning systems, outdoor units are often installed in the recesses of building facades and shaded by louvres; however, different unit installation positions and louvre blade angles affect the thermal environment around the outdoor unit and the energy efficiency ratio (EER) of the air conditioner. In this study, the effects of the outdoor unit installation position and louvre blade angle on the EER when a single outdoor unit was installed in a recess were investigated by experiments on a 1.5 hp air conditioner (rated power of the air conditioner is 3.5 kW), and the influence of the spacing and angle between two outdoor units on the air conditioner EER when two outdoor units were installed in the same recess was explored. The results of the research indicate that when a single outdoor unit is installed in the recess, the EER increases with an increase in the distance between the inlet of the outdoor unit and the wall. To meet the three-level standard of air conditioner EERs, the distance between the inlet and wall needs to be greater than 300 mm. The EER first increased and then decreased slowly with the increase in the distance between the outdoor unit outlet and louvre; thus, the distance between the outlet and louvre should not be less than 300 mm. The EER first increased and then decreased with the increase in the blade angle, and thus, the blade angle should not be greater than 20°. When two outdoor units are installed in the same recess, each installation mode, “horizontal installation” (same height and collinear), “perpendicular installation” (same height and perpendicular), “angle installation” (same height and obtuse angle), and “up and down parallel installation” (different heights and parallel), has an optimum installation distance and angle.

Cooling Seasonal Performance Factor (CSPF) Application in Indonesia for Residential Air Conditioning (AC) Unit

As an archipelago country located around the equator line, Indonesia has a broad ambient temperature range of varying atmospheric conditions. This issue should be concerned with applying ISO 16358-1 to calculate Seasonal Energy Efficient Ratio (SEER) on cooling, or so-called the Cooling Seasonal Performance Factor (CSPF). The ISO 16358-1 recommend a set of bin temperature which can be used as the basis for calculating the CSPF. The research objectives are to compare the local ambient temperature of four cities in Indonesia (Jakarta, Bandung, Pontianak, and Palembang) with the ISO bin temperature. The normal distribution graph of temperature for every four cities in Indonesia shows a remarkable difference from the ISO bin temperature. Jakarta’s most occurring temperature range is 25 – 30 °C, Bandung is 21 – 23 °C, Pontianak is 24 – 26 °C, and Palembang is 24 – 26 °C, annually. Those numbers were compared to the ISO, which has the most occurring temperature range around 24 - 28 °C. The result on CSPF calculation of AC unit sample in the range of 4,000 – 17,000 Btu/hr (both non-inverter and inverter) using Indonesia local bin temperature compared with the ISO bin temperature has an average range of 5.10%. It was concluded that Indonesia’s local ambient temperature affects the CSPF value, especially on the AC inverter unit. On the other hand, the relatively small difference value of CSPF has an advantage in applying the ISO bin temperature for future Indonesia’s energy conservation policy. It could lead to harmonizing with other South-East Asian (ASEAN) countries specifically, and another country also applying the ISO 16358-1, in general.

Investigating the relationship between residential AC, indoor temperature and relative humidity in Indian dwellings

Residential electricity consumption (REC) in India has tripled in the past two decades accounting for 24% of the overall electricity consumption during 2018-19. Residential air conditioning (AC) usage is responsible for about 20%-40% of REC in India. This paper investigates the relationship of residential AC use with indoor temperature and relative humidity (RH) using concurrent time-series monitoring data gathered in eight dwellings during summer and monsoon seasons. Contextual data about the dwelling (physical) and household characteristics were gathered using face-to-face interview based surveys. The dwellings were located in Hyderabad representing the composite climate of India. The mean daily electricity consumption was found to be higher in summer (11.5kWh) possibly due to the higher usage of AC (because of higher ambient conditions) as compared to 6.5kWh/day during monsoon season. Binary logistic regression identified the trigger indoor temperature and RH at which AC was likely to be switched on in the summer as 29 °C - 31.9 °C for indoor temperature and 36%-38.9% RH. In the monsoon season AC was predicted to come on sooner at 26°C-28.9°C but at higher RH range of 59%-61.9%. These empirical findings can be used to reduce residential cooling energy demand through smart management of ACs in Indian dwellings.

Simulation of rubber grommets and correlation with test at low frequencies

Residential air conditioning units include several sources which can lead to vibrational and noise issues. The most important structure-borne source is the compressor which controls the noise and vibration in certain frequency ranges. Compressors are mounted on four relatively stiff rubber grommets which partially isolate the basepan from the compressor motion while also ensuring that the compressor does not move too much. In this work, the grommets are simulated using the finite element method and results are correlated with measurement results with good agreement. It is demonstrated that the hyperelastic properties of the grommets should be increased due to the Payne effect to improve correlation.