{"action":"created","issue":{"url":"https://api.github.com/repos/tbeu/Modelica/issues/1530","repository_url":"https://api.github.com/repos/tbeu/Modelica","labels_url":"https://api.github.com/repos/tbeu/Modelica/issues/1530/labels{/name}","comments_url":"https://api.github.com/repos/tbeu/Modelica/issues/1530/comments","events_url":"https://api.github.com/repos/tbeu/Modelica/issues/1530/events","html_url":"https://github.com/tbeu/Modelica/issues/1530","id":197603767,"number":1530,"title":"PartialSimpleIdealGasMedium uses different offsets in BaseProperties and in specifidInternalEnergy","user":{"login":"modelica-trac-importer","id":22202507,"avatar_url":"https://avatars.githubusercontent.com/u/22202507?v=3","gravatar_id":"","url":"https://api.github.com/users/modelica-trac-importer","html_url":"https://github.com/modelica-trac-importer","followers_url":"https://api.github.com/users/modelica-trac-importer/followers","following_url":"https://api.github.com/users/modelica-trac-importer/following{/other_user}","gists_url":"https://api.github.com/users/modelica-trac-importer/gists{/gist_id}","starred_url":"https://api.github.com/users/modelica-trac-importer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/modelica-trac-importer/subscriptions","organizations_url":"https://api.github.com/users/modelica-trac-importer/orgs","repos_url":"https://api.github.com/users/modelica-trac-importer/repos","events_url":"https://api.github.com/users/modelica-trac-importer/events{/privacy}","received_events_url":"https://api.github.com/users/modelica-trac-importer/received_events","type":"User","site_admin":false},"labels":[{"id":506762997,"url":"https://api.github.com/repos/tbeu/Modelica/labels/bug","name":"bug","color":"ee0701","default":true},{"id":506769720,"url":"https://api.github.com/repos/tbeu/Modelica/labels/L:Media","name":"L:Media","color":"0000aa","default":false},{"id":506770144,"url":"https://api.github.com/repos/tbeu/Modelica/labels/P:%20high","name":"P: high","color":"ff6666","default":false}],"state":"open","locked":false,"assignee":{"login":"beutlich","id":14896695,"avatar_url":"https://avatars.githubusercontent.com/u/14896695?v=3","gravatar_id":"","url":"https://api.github.com/users/beutlich","html_url":"https://github.com/beutlich","followers_url":"https://api.github.com/users/beutlich/followers","following_url":"https://api.github.com/users/beutlich/following{/other_user}","gists_url":"https://api.github.com/users/beutlich/gists{/gist_id}","starred_url":"https://api.github.com/users/beutlich/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/beutlich/subscriptions","organizations_url":"https://api.github.com/users/beutlich/orgs","repos_url":"https://api.github.com/users/beutlich/repos","events_url":"https://api.github.com/users/beutlich/events{/privacy}","received_events_url":"https://api.github.com/users/beutlich/received_events","type":"User","site_admin":false},"assignees":[{"login":"beutlich","id":14896695,"avatar_url":"https://avatars.githubusercontent.com/u/14896695?v=3","gravatar_id":"","url":"https://api.github.com/users/beutlich","html_url":"https://github.com/beutlich","followers_url":"https://api.github.com/users/beutlich/followers","following_url":"https://api.github.com/users/beutlich/following{/other_user}","gists_url":"https://api.github.com/users/beutlich/gists{/gist_id}","starred_url":"https://api.github.com/users/beutlich/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/beutlich/subscriptions","organizations_url":"https://api.github.com/users/beutlich/orgs","repos_url":"https://api.github.com/users/beutlich/repos","events_url":"https://api.github.com/users/beutlich/events{/privacy}","received_events_url":"https://api.github.com/users/beutlich/received_events","type":"User","site_admin":false}],"milestone":{"url":"https://api.github.com/repos/tbeu/Modelica/milestones/52","html_url":"https://github.com/tbeu/Modelica/milestone/52","labels_url":"https://api.github.com/repos/tbeu/Modelica/milestones/52/labels","id":2214855,"number":52,"title":"MSL3.2.1+build.3","description":"Plan as of 84th Modelica Design Meeting:\n 1. Freeze date for maintenance build: Dec 22, 2014\n 2. Leo will run regression testing an fill a ticket for all models with non-obvious differences by Jan 2, 2015 (check \n    wiki:HowTo/MAP-LIB/ModelicaStandardLibrary/RegressionTesting for instructions how to replicate regression tests)\n 3. All library officers should react within one week, until Jan 9, 2015 (either explain the difference or fix the bug)\n 4. A web meeting is scheduled shortly after Jan 9, 2015 for a quick review and then build `v3.2.1+build.3-beta.2`\n\n","creator":{"login":"modelica-trac-importer","id":22202507,"avatar_url":"https://avatars.githubusercontent.com/u/22202507?v=3","gravatar_id":"","url":"https://api.github.com/users/modelica-trac-importer","html_url":"https://github.com/modelica-trac-importer","followers_url":"https://api.github.com/users/modelica-trac-importer/followers","following_url":"https://api.github.com/users/modelica-trac-importer/following{/other_user}","gists_url":"https://api.github.com/users/modelica-trac-importer/gists{/gist_id}","starred_url":"https://api.github.com/users/modelica-trac-importer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/modelica-trac-importer/subscriptions","organizations_url":"https://api.github.com/users/modelica-trac-importer/orgs","repos_url":"https://api.github.com/users/modelica-trac-importer/repos","events_url":"https://api.github.com/users/modelica-trac-importer/events{/privacy}","received_events_url":"https://api.github.com/users/modelica-trac-importer/received_events","type":"User","site_admin":false},"open_issues":1,"closed_issues":56,"state":"closed","created_at":"2016-12-25T13:01:13Z","updated_at":"2016-12-26T16:45:52Z","due_on":"2014-03-15T07:00:00Z","closed_at":"2016-12-25T13:01:13Z"},"comments":7,"created_at":"2016-12-26T16:44:22Z","updated_at":"2016-12-26T16:46:26Z","closed_at":null,"body":"**Reported by otter on 27 Jun 2014 15:53 UTC**\nWhen simulating the test model ModelicaTest.Media.TestAllProperties.SimpleAir an error occurs. The reason are different offsets in the medium model.\n\nIn PartialSimpleIdealGasMedium.BaseProperties:\n```\nh = specificEnthalpy_pTX(p,T, X);  // = cp_const*(T - T0);\nu = h - R*T; // = (cp_const - R)*T - cp_const*T0\n```\nIn PartialSimpleIdealGasMedium.specificInternalEnergy:\n```\nu = (cp_const - R)*(T - T0);  \n    // = (cp_const - R)*T - cp_const*T0 - (cp_const - R)*T0\n```\nTherefore in the first case the offset is\n cp_const\\*T0\nand in the second case it is \n (cp_const - R)\\*T0\n\n\n----\n\nMigrated-From: https://trac.modelica.org/Modelica/ticket/1530"},"comment":{"url":"https://api.github.com/repos/tbeu/Modelica/issues/comments/269226037","html_url":"https://github.com/tbeu/Modelica/issues/1530#issuecomment-269226037","issue_url":"https://api.github.com/repos/tbeu/Modelica/issues/1530","id":269226037,"user":{"login":"modelica-trac-importer","id":22202507,"avatar_url":"https://avatars.githubusercontent.com/u/22202507?v=3","gravatar_id":"","url":"https://api.github.com/users/modelica-trac-importer","html_url":"https://github.com/modelica-trac-importer","followers_url":"https://api.github.com/users/modelica-trac-importer/followers","following_url":"https://api.github.com/users/modelica-trac-importer/following{/other_user}","gists_url":"https://api.github.com/users/modelica-trac-importer/gists{/gist_id}","starred_url":"https://api.github.com/users/modelica-trac-importer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/modelica-trac-importer/subscriptions","organizations_url":"https://api.github.com/users/modelica-trac-importer/orgs","repos_url":"https://api.github.com/users/modelica-trac-importer/repos","events_url":"https://api.github.com/users/modelica-trac-importer/events{/privacy}","received_events_url":"https://api.github.com/users/modelica-trac-importer/received_events","type":"User","site_admin":false},"created_at":"2016-12-26T16:46:26Z","updated_at":"2016-12-26T16:46:26Z","body":"**Comment by otter on 6 Jan 2015 18:56 UTC**\nReplying to [comment:4 hubertus]:\n> I don't think that the comment above is necessarily correct, and it may all be about a different use of terms between \"Ideal Gas\" and \"Perfect Gas\". In the references that I know, \n> \n> - the enthalpy for an ideal gas can have an arbitrary reference temperature \n> - the internal energy, relativ to that reference, can be greater than the enthalpy. \n> \n> This is consistent with how the much more complex NASA ideal gas is implemented, where the reference temperature can be set to either 0 K or 25 Deg Celsius.\n> \n> What the commenter writes may however be true for a \"Perfect Gas\", I'd have to check that, and typically a \"Perfect Gas\" has a constant cp. This is however not consistent in the literature and a model with a constant cp is also referred to as an \"ideal gas\". \n\nIn SingleGasNasa the following equations are present:\n```\nh = IdealGases.Common.Functions.h_T(data,state.T);\nu = IdealGases.Common.Functions.h_T(data,state.T) - data.R*state.T;\n```\nI did not find the place where the reference temperature is set. But independently of the reference point (assuming that the same \"data\" is used), then it follows from the above equations:\n```\nu = h - data.R*state.T\n# h - state.p/d\n```\nTherefore, also for the NASA medium the equation h = u + p\\*v holds, as it should be.\n\nMy conclusion: The medium should be fixed as proposed in the ticket.\n\n"}}
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