CAPACITY ASSESSMENT OF A WINDOW AIR-CONDITIONER RETROFITTED WITH A REFRIGERANT MIXTURE

M. HERBERT RAJ,D. MOHAN LAL,D. B. JABARAJ 대한설비공학회 2011 International Journal Of Air-Conditioning and Refr Vol.19 No.1

R22 being a HCFC is to be phased out soon as per the Montreal protocol. This paper presents the experimental performance study of an air-conditioner retrofitted with M20 (a refrigerant mixture of R407C, R600a and R290 in the mass fraction 80:10.96:9.04 respectively). M20 is considered as a substitute for R22 in window air-conditioners with mineral oil as the compressor lubricant. Previously, the performance of the same mixture has been reported with 19% extra condenser length as compared to that in the R22 system. In this study, experiments were conducted in a 5.25 kW window airconditioner to assess the potential of M20 as a retrofit refrigerant without making any system alteration other than changing the capillary. The system performance study was carried out with R22 and later with the M20 charge in a psychrometric test facility as per BIS and ASHRAE standards. Experimental results showed that with the M20, the system had 4.18% to 7.47% lower cooling capacity with respect to that of R22. The COP for the M20 refrigerant was lower, in the range of 0.58% to 7.78% than that of R22. Hence, M20 can be used as a drop- in-substitute for R22 in window air-conditioners but with a marginal reduction in cooling capacity.

Analgesic and anti-inflammatory activity of a polyherbal formulation (PHFAROGH)

Mohan, M,Gulecha, VS,Aurangabadkar, VM,Balaraman, R,Austin, A,Thirugnanasampathan, S Kyung Hee Oriental Medicine Research Center 2009 Oriental pharmacy and experimental medicine Vol.9 No.3

The effect of arogh, a polyherbal formulation-PHF [each 3 g powder contained Nelumbo nucifera G. (0.24 g), Hemidesmus indicus R. (0.24 g), Zingiber officinale R. (0.24 g), Terminalia chebula R. (0.24 g), Quercus infectoria O. (0.12 g), Hibiscus rosa-sinensis L. (0.24 g), Rosa damascene M.(0.24 g), Eclipta alba H.(0.24 g), Glycyrrhiza glabra L. (0.24 g)] was investigated in various experimental models of pain and inflammation. Analgesic activity of PHF was studied in mice using acetic acid induced writhing, tail immersion and hot plate methods. Anti-inflammatory activity of PHF was studied in rats using carrageenan induced hind paw edema and formalin induced rat paw edema methods. PHF significantly (P < 0.05) reduced the number of writhings, increased latency to flick tail in tail immersion method and elevated the mean basal reaction time in hot plate method. PHF significantly (P < 0.05) inhibited carrageenan induced hind paw edema and formalin induced rat paw edema. The PHF was tested at dose of 30, 100, 300 and 500 mg/kg.

Analgesic and anti-inflammatory activity of a polyherbal formulation (PHFAROGH)

M Mohan,VS Gulecha,VM Aurangabadkar,R Balaraman,S Thirugnanasampathan,A Austin 경희대학교 융합한의과학연구소 2009 Oriental Pharmacy and Experimental Medicine Vol.9 No.3

The effect of arogh, a polyherbal formulation-PHF [each 3 g powder contained Nelumbo nucifera G. (0.24 g), Hemidesmus indicus R. (0.24 g), Zingiber officinale R. (0.24 g), Terminalia chebula R. (0.24 g), Quercus infectoria O. (0.12 g), Hibiscus rosa-sinensis L. (0.24 g), Rosa damascene M.(0.24 g), Eclipta alba H.(0.24 g), Glycyrrhiza glabra L. (0.24 g)] was investigated in various experimental models of pain and inflammation. Analgesic activity of PHF was studied in mice using acetic acid induced writhing, tail immersion and hot plate methods. Anti-inflammatory activity of PHF was studied in rats using carrageenan induced hind paw edema and formalin induced rat paw edema methods. PHF significantly (P < 0.05) reduced the number of writhings, increased latency to flick tail in tail immersion method and elevated the mean basal reaction time in hot plate method. PHF significantly (P < 0.05) inhibited carrageenan induced hind paw edema and formalin induced rat paw edema. The PHF was tested at dose of 30, 100, 300 and 500 mg/kg. The effect of arogh, a polyherbal formulation-PHF [each 3 g powder contained Nelumbo nucifera G. (0.24 g), Hemidesmus indicus R. (0.24 g), Zingiber officinale R. (0.24 g), Terminalia chebula R. (0.24 g), Quercus infectoria O. (0.12 g), Hibiscus rosa-sinensis L. (0.24 g), Rosa damascene M.(0.24 g), Eclipta alba H.(0.24 g), Glycyrrhiza glabra L. (0.24 g)] was investigated in various experimental models of pain and inflammation. Analgesic activity of PHF was studied in mice using acetic acid induced writhing, tail immersion and hot plate methods. Anti-inflammatory activity of PHF was studied in rats using carrageenan induced hind paw edema and formalin induced rat paw edema methods. PHF significantly (P < 0.05) reduced the number of writhings, increased latency to flick tail in tail immersion method and elevated the mean basal reaction time in hot plate method. PHF significantly (P < 0.05) inhibited carrageenan induced hind paw edema and formalin induced rat paw edema. The PHF was tested at dose of 30, 100, 300 and 500 mg/kg.

Multilevel Inverter to Reduce Common Mode Voltage in AC Motor Drives Using SPWM Technique

Mohan M. Renge,Hiralal M. Suryawanshi 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.1

In this paper, an approach to reduce common-mode voltage (CMV) at the output of multilevel inverters using a phase opposition disposed (POD) sinusoidal pulse width modulation (SPWM) technique is proposed. The SPWM technique does not require computations therefore, this technique is easy to implement on-line in digital controllers. A good tradeoff between the quality of the output voltage and the magnitude of the CMV is achieved in this paper. This paper realizes the implementation of a POD-SPWM technique to reduce CMV using a five-level diode clamped inverter for a three phase induction motor. Experimental and simulation results demonstrate the feasibility of the proposed technique.

DC Fault Protection in Multi-terminal VSC-Based HVDC Transmission Systems with Current Limiting Reactors

M. Mohan,K. Panduranga Vittal 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.1

Multi-terminal VSC-based HVDC transmission system is the recent interest for grid integration of large-scale offshore wind farms. Protection of multi-terminal voltage source converters (VSC)-based HVDC transmission systems against DC faults is challenging. This paper presents a single-ended protection scheme for DC faults in a three-terminal VSC-HVDC transmission system. The under-voltage criterion is used to distinguish the DC faults from the transient and normal conditions. The rate of change of DC voltage and current as well as the variation of transient energy is used to discriminate the internal faults from the external faults. The DC fault current has very high value within a few milliseconds during the transient phases such as the capacitor discharging and diode freewheeling stages. Therefore, current limiting reactors are introduced in series with the DC circuit breaker to maintain the DC fault current within the breaker capacity. The single-ended protection scheme is tested with the three-terminal VSC-HVDC transmission system with current limiting reactors for various DC fault conditions. The DC fault data is generated from PSCAD/EMTDC simulation and the protection scheme is tested in MATLAB environment. Test results show that the proposed protection scheme gives reliable protection for the DC faults in a three-terminal VSC-HVDC transmission system.

Poly(N-isopropylacrylamide-co-sodium acrylate) hydrogels: Interactions with surfactants

Mohan, Y. M.,Joseph, D. K.,Geckeler, K. E. Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.103 No.5

<P>Poly(N-isopropylacrylamide-co-sodium acrylate) [poly(NIPAM-co-SA)] hydrogels were modified with three different kind of surfactants (cationic, anionic, and nonionic) to study the effect on the swelling properties. The structural variation of the surfactant-modified hydrogels was investigated in detail. The interaction between the surfactants and the hydrogel varies and strictly depends on the surfactant type. The variation in thermal stability of the modified surfactant hydrogels was investigated and compared with unmodified hydrogel. Further, the hydrogel swelling/diffusion kinetic parameters were investigated and diffusion of water into hydrogel was found to be of the non-Fickian transport mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3423–3430, 2007</P>

Anxiolytic activity of standardized extract of Korean ginseng - a study on exploratory behavior

Mohan, M,Kasture, SB,Balaraman, R Kyung Hee Oriental Medicine Research Center 2005 Oriental pharmacy and experimental medicine Vol.5 No.4

The roots of the plant Korean ginseng have been extensively used in the traditional Chinese herbal medicine. We investigated the standardized extract of Korean ginseng on animal models of anxiety based on exploratory behavior. Korean ginseng extract (KGE) (3, 10 and 30 mg/kg) was administered intra-peritoneally. The anxiolytic activity was studied using elevated plus maze (EPM) paradigm, light/dark apparatus (LDA), open field apparatus (OFA) and the hole board apparatus (HBA). Diazepam (1mg/kg) was used as a standard anxiolytic drug. In EPM, KGE (10 mg/kg) significantly (P < 0.05) increased the time spent in open arms and the number of entries in open arms. In LDA, KGE (10 mg/kg) increased the number of transitions. In OFA, KGE (3 and 10 mg/kg) significantly increased (P < 0.05) the number of squares traversed. In HBA the number of head pokes were significantly increased with KGE (3 and 10 mg/kg). KGE at all selected doses did not affect the motor coordination. Thus, the study suggests that saponin containing standardized Korean ginseng extract possess anxiolytic activity.

Antihypertensive activity of Zingiber officinale and Korean ginseng in experimentally induced hypertension in rats

M Mohan,R Balaraman,SB Kasture 경희대학교 융합한의과학연구소 2007 Oriental Pharmacy and Experimental Medicine Vol.7 No.3

We investigated the antihypertensive effect of Pet ether extract (PE) of ginger rhizome; its toluene fraction (TF) and Korean ginseng extract (KGE) in deoxycorticosterone acetate (DOCA) – salt induced and fructose induced hypertensive rats. In DOCA model, DOCA (25 mg/kg, once a week; s.c) was administered in uninephrectomised animals for 4 w. PE (50 mg/kg/day; p.o), TF (10 mg/kg/day; p.o) and KGE (30 mg/kg/day; p.o) were evaluated for their antihypertensive effect. In the fructose model, drinking water was replaced with fructose (10%) for five weeks to induce hypertension. PE (50 mg/kg/day; p.o) and KGE (30 mg/kg/day; p.o) were assessed for its antihypertensive effect in fructose model. After completion of the treatment schedule, vascular reactivity to various agonists like 5-HT, noradrenaline, adrenaline, phenylbiguanide and acetylcholine were recorded in rats of both the models. A cumulative dose response curve (CDRC) of 5-HT was carried out in isolated rat fundus strip of the fructose induced hypertensive rats. Chronic administration of PE (50 mg/kg/day; p.o), TF (10 mg/kg/day; p.o), and KGE (30 mg/kg/day; p.o) significantly reduced the blood pressure in DOCA salt whereas PE (50 mg/kg/day; p.o) and KGE (30 mg/kg/day; p.o) reduced the blood pressure in fructose induced hypertensive rats. Treatment with PE (50 mg/kg/day; p.o) and KGE (30 mg/kg/day; p.o) in fructose model for five weeks shifted the CDRC towards the right on rat fundus. The mechanism of action may partly involve the serotonergic antagonistic property.

Anxiolytic effect of chronic ginseng treatment using elevated T-maze in mice

M Mohan,SB Kasture,R Balaraman 경희대학교 융합한의과학연구소 2007 Oriental Pharmacy and Experimental Medicine Vol.7 No.1

The roots of the plant Korean ginseng have been extensively used in the traditional Chinese herbal medicine. The effects of chronic administration of Korean ginseng extract (KGE) were investigated on two different anxiety models: the elevated T-maze (for inhibitory avoidance and escape measurements) and the open field test (OFT). Diazepam (1 mg/kg), KGE (10, 30 and 100 mg/kg) were administered orally for 15 days. On the 14th day, mice were previously exposed for 30 min to one of the open arms of the T-maze, 24 h before the test. On 15th day, mice had two exposures to the enclosed and open arm of the elevated T-maze followed by exposure to the open field apparatus. The number of line crossings in the apparatus was used to assess locomotor changes. Cumulative Concentration Response Curve of 5-HT was plotted using rat fundus which were pre-treated in a similar way. Treatment with Diazepam (1 mg/kg) and KGE (10, 30 and 100 mg/kg) significantly (P < 0.05) impaired inhibitory avoidance performance but did not impair escape latency. In OFT, diazepam facilitated locomotion as compared to vehicle and other treatment groups. KGE at any of the selected doses did not impair locomotion. Concentration response curve of 5-HT was shifted towards the right with suppression of maxima in rats treated with KGE. The results suggest that KGE exerts anxiolytic like behaviour in a specific subset of defensive behaviour, particularly those related to generalized anxiety disorder.

Anxiolytic effect of chronic ginger treatment using elevated T-maze in mice

Mohan M,Kasture SB,Balaraman R Kyung Hee Oriental Medicine Research Center 2006 Oriental pharmacy and experimental medicine Vol.6 No.3

We investigated the effects of chronic administration of different extracts of ginger rhizome [pet ether extract (PE); toluene fraction (TF) of pet ether extract] on anxiety models: the elevated T-maze (ETM) (for inhibitory avoidance and escape measurements) and the open field test. Ondansetron (1 mg/kg), FE (10, 30 &100 mg/kg) and TF (10 & 30 mg/kg) were administered orally for 15 days. On the $14^{th}$ day mice were previously exposed for 30 min to one of the open arms of the T-maze, 24 h before the test. On $15^{th}$ day mice had two exposures to the enclosed and open arm of the ETM followed by exposure to the open field apparatus. The number of line crossings in the apparatus was used to assess locomotor changes. Cumulative Concentration Response Curve of 5-HT was plotted using rat fundus which were pretreated in a similar way. Treatment with Ondansetron (1 mg/kg), PE (100 mg/kg), TF (10 mg/kg) and TF (30 mg/kg) significantly (P<0.05) impaired inhibitory avoidance performance but did not impair escape latency. Concentration response curve of 5-HT was shifted towards the right with suppression of maxima in rats treated with PE and TF. The results suggest that PE and TF of Ginger rhizome exerts anxiolytic like behaviour in a specific subset of defensive behaviour, particularly those related to generalized anxiety disorder.