Evaluation of performance of Heat pump system using R32 and HFO mixed refrigerant.

Recently several refrigerants have been lined up as candidate alternatives to R410A in order to prevent further global warming and to promote saving energy. We have selected R32 from among these candidates; however it is important to continue comparing it to other refrigerants in search for an even better choice. Therefore we carried out evaluation of the new R32/R1234ze(50/50) refrigerant for capacity, by comparing its COP and compressor discharge temperature etc. to those of R410A, and the results of R32. We also conducted analysis regarding the drop of COP during Cooling operation in case of high outside temperature. As a result, we found that the COP of R32 is superior to the other refrigerants due especially to its small amount of pressure loss. As the discharge temperature for both the R32/R1234ze(50/50) refrigerant and R32 was roughly the same, we re-confirmed that there is no problem using R32. Additionally, for non-azeotropic refrigerants such as R32/R1234ze(50/50), a Temperature Glide occurs during phase change. During the current evaluation, we came across a number of performance degradation phenomena thought to be caused by this glide. From the above, we confirmed that R32 is indeed the best candidate at present. We will continue to carry out evaluation in search for a better candidate

Research on Optimization of Heat exchanger in Heat pump using R32 and HFO-mixed Refrigerant

Recently several refrigerants have been lined up as candidate alternatives to R410A in order to mitigate further global warming and to promote saving energy. We have selected R32 from among these candidates; however it is important to continue comparing it to other refrigerants in search for an even better choice. Therefore we carried out the drop-in test of the new refrigerant R32/R1234yf/R125(67/26/7) by comparing its COP and compressor discharge temperature etc. to those of R410A, R32/R1234ze(70/30), and R32, using residential mini-split type air conditioner. As a result, we confirm the performance of new refrigerant R32/R1234yf/R125(67/26/7) is not better than that of R32, since they have loss due to refrigerant pressure drop. However the results above are not assumed to be fair since they are obtained by means of heat exchangers optimized for R32. Therefore we evaluate the new refrigerant candidate with optimization of heat exchangers for them by detail simulation including pass configuration. After that, we conclude that R32 is better than other candidate at present

Evaluation of Performance of Heat Pump using R32 and HFO-mixed Refrigerant by Refrigeration Cycle Simulation and Loss analysis

R32 was selected as the alternative for R410A for mini-split air conditioners/heat pumps in Japan and have already phased out R410A in residential market. Recently several new alternatives for R410A have been proposed in order to achieve more close capacity to R410A and mitigate high discharge temperature issue of R32 as well as to reduce energy consumption. We selected R32 from among the candidates a few years ago; however it is important to continue comparing it to new candidates in search for an even better choice. We carried out the drop-in tests of the new refrigerant R32/R125/R1234yf (67/7/26) by comparing its COP and especially pressure loss to those of R410A, R32/R1234ze(E)(70/30), and R32, using residential mini-split type air conditioner. We conducted the drop-in tests by two types of method, actual measuring and especially simulated calculation. Adjusting compressor suction superheat and the amount of refrigerant charged into the system. Moreover, we measured the performance of the system with changing compressor speed in the wide range by variable frequency drive. Furthermore, we compared electricity consumption at the constant capacities, and analyzed the results precisely by loss analysis. As a result, we found that the COP of R32/R125/R1234yf (67/7/26) is better than R410A in many conditions and it achieves very close capacity to R410A, but COP at the same capacity is not as high as R32. The reason is that pressure losses are increased by adding R125 and R1234yf to R32. It was clarified, comparing losses with R410A, R32/1234ze(70/30), and R32. From the above, we confirmed that R32 is still the best choice at present. However, we will continue searching for a better alternative.

Performance Evaluation of Heat pump System using R32 and HFO-mixed Refrigerant in High Ambient Temperature.

R32 was selected as the alternative for R410A for mini-split air conditioners/heat pumps and already phased out R410A in residential market in Japan. Recently several new alternatives for R410A have been proposed in order to achieve more close capacity to R410A and mitigate high discharge temperature issue of R32 as well as to reduce energy consumption. We selected R32 from among the candidates a few years ago; however it is important to continue comparing it to new candidates in search for an even better choice. We carried out performance evaluation for the lower GWP refrigerant R32/R125/R1234yf (67/7/26) and R32. We also conducted the experiments in cooling operation at high ambient temperature. As the result, we found that the COP of R32 is superior to the blend because of its latent heat characteristic. In particular, as condensing temperature increases such as at high ambient temperature operation, latent heat of the blend obtains even smaller. Therefore, advantage of R32 in COP becomes more significant at high ambient conditions. From the above, we consider that R32 is still the best refrigerant at present. However, we will continue investigation in search for a better refrigerant

Evaluation and Optimization of System Performance using HFO-mix Refrigerants for VRF and Mini-split Air-Conditioner

Global demand for air conditioning is expected to increase continuously. In order to minimize the impact on the climate as a total amount of CO2 equivalent, it is essential to continue to search for better refrigerants. On the other hand, product size and cost are important factors in providing value to users. This time, while using the experiment result of the mini-split type air-conditioner reported in the past, in addition, we conducted a new experiment on multi-type VRF air-conditioner. Then, the difference in COP performance between R-410A and alternative candidate refrigerants was evaluated. In addition, we studied the product design using R-452 B, R-454 B by simulation and compare the size when the performance is made identical by changing the system specifications with alternative refrigerant candidates. As a result, common results were obtained in both systems. It was found that R-452B and R-454B have better performance than R-410A. On the other hand, it was found that these refrigerants need to increase both the indoor heat exchanger and the outdoor heat exchanger to 120% in order to obtain the same performance as R-32

Magnetic dichroism in angular-resolved hard X-ray photoelectron spectroscopy from buried layers

This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard X-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co$_2$FeAl layer buried beneath the IrMn layer. A pronounced magnetic dichroism is found in the Co and Fe $2p$ states of both materials. The localization of the magnetic moments at the Fe site conditioning the peculiar characteristics of the Co$_2$FeAl Heusler compound, predicted to be a half-metallic ferromagnet, is revealed from the magnetic dichroism detected in the Fe $2p$ states